Introduce nvim namespace: Move files.

Move files from src/ to src/nvim/.
- src/nvim/ becomes the new root dir for nvim executable sources.
- src/libnvim/ is planned to become root dir of the neovim library.

src/nvim/path.h

@@ -0,0 +1,128 @@
+#ifndef NEOVIM_PATH_H
+#define NEOVIM_PATH_H
+
+#include "func_attr.h"
+#include "types.h"
+#include "garray.h"
+
+/// Return value for the comparison of two files. Also @see path_full_compare.
+typedef enum file_comparison {
+  kEqualFiles = 1,        ///< Both exist and are the same file.
+  kDifferentFiles = 2,    ///< Both exist and are different files.
+  kBothFilesMissing = 4,  ///< Both don't exist.
+  kOneFileMissing = 6,    ///< One of them doesn't exist.
+  kEqualFileNames = 7     ///< Both don't exist and file names are same.
+} FileComparison;
+
+/// Compare two file names.
+///
+/// @param s1 First file name. Environment variables in this name will be
+///   expanded.
+/// @param s2 Second file name.
+/// @param checkname When both files don't exist, only compare their names.
+/// @return Enum of type FileComparison. @see FileComparison.
+FileComparison path_full_compare(char_u *s1, char_u *s2, int checkname);
+
+/// Get the tail of a path: the file name.
+///
+/// @param fname A file path.
+/// @return
+///   - Empty string, if fname is NULL.
+///   - The position of the last path separator + 1. (i.e. empty string, if
+///   fname ends in a slash).
+///   - Never NULL.
+char_u *path_tail(char_u *fname);
+
+/// Get pointer to tail of "fname", including path separators.
+///
+/// Takes care of "c:/" and "//". That means `path_tail_with_sep("dir///file.txt")`
+/// will return a pointer to `"///file.txt"`.
+/// @param fname A file path. (Must be != NULL.)
+/// @return
+///   - Pointer to the last path separator of `fname`, if there is any.
+///   - `fname` if it contains no path separator.
+///   - Never NULL.
+char_u *path_tail_with_sep(char_u *fname);
+
+/// Get the next path component of a path name.
+///
+/// @param fname A file path. (Must be != NULL.)
+/// @return Pointer to first found path separator + 1.
+/// An empty string, if `fname` doesn't contain a path separator,
+char_u *path_next_component(char_u *fname);
+
+int vim_ispathsep(int c);
+int vim_ispathsep_nocolon(int c);
+int vim_ispathlistsep(int c);
+void shorten_dir(char_u *str);
+int dir_of_file_exists(char_u *fname);
+int vim_fnamecmp(char_u *x, char_u *y);
+int vim_fnamencmp(char_u *x, char_u *y, size_t len);
+char_u *concat_fnames(char_u *fname1, char_u *fname2, int sep)
+  FUNC_ATTR_NONNULL_RET;
+int unix_expandpath(garray_T *gap, char_u *path, int wildoff, int flags,
+                    int didstar);
+int gen_expand_wildcards(int num_pat, char_u **pat, int *num_file,
+                         char_u ***file,
+                         int flags);
+void addfile(garray_T *gap, char_u *f, int flags);
+char_u *get_past_head(char_u *path);
+char_u *concat_str(char_u *str1, char_u *str2) FUNC_ATTR_NONNULL_RET;
+void add_pathsep(char_u *p);
+char_u *FullName_save(char_u *fname, int force);
+void simplify_filename(char_u *filename);
+char_u *find_file_name_in_path(char_u *ptr, int len, int options,
+                               long count,
+                               char_u *rel_fname);
+int path_is_url(char_u *p);
+int path_with_url(char_u *fname);
+int vim_isAbsName(char_u *name);
+int vim_FullName(char_u *fname, char_u *buf, int len, int force);
+char_u *fix_fname(char_u *fname);
+int after_pathsep(char_u *b, char_u *p);
+int same_directory(char_u *f1, char_u *f2);
+int pathcmp(const char *p, const char *q, int maxlen);
+int mch_expandpath(garray_T *gap, char_u *path, int flags);
+
+/// Try to find a shortname by comparing the fullname with the current
+/// directory.
+///
+/// @param full_path The full path of the file.
+/// @return
+///   - Pointer into `full_path` if shortened.
+///   - `full_path` unchanged if no shorter name is possible.
+///   - NULL if `full_path` is NULL.
+char_u *path_shorten_fname_if_possible(char_u *full_path);
+
+/// Try to find a shortname by comparing the fullname with `dir_name`.
+///
+/// @param full_path The full path of the file.
+/// @param dir_name The directory to shorten relative to.
+/// @return
+///   - Pointer into `full_path` if shortened.
+///   - NULL if no shorter name is possible.
+char_u *path_shorten_fname(char_u *full_path, char_u *dir_name);
+
+int expand_wildcards_eval(char_u **pat, int *num_file, char_u ***file,
+                          int flags);
+int expand_wildcards(int num_pat, char_u **pat, int *num_file, char_u *
+                     **file,
+                     int flags);
+int match_suffix(char_u *fname);
+
+/// Get the absolute name of the given relative directory.
+///
+/// @param directory Directory name, relative to current directory.
+/// @return `FAIL` for failure, `OK` for success.
+int path_full_dir_name(char *directory, char *buffer, int len);
+
+// Append to_append to path with a slash in between.
+int append_path(char *path, const char *to_append, int max_len);
+
+/// Check if the given file is absolute.
+///
+/// This just checks if the file name starts with '/' or '~'.
+/// @return `TRUE` if "fname" is absolute.
+int path_is_absolute_path(const char_u *fname);
+
+#endif