Removes 'proto' dir

See #137 for the issue.

Every header in the proto directory was:

* Given include guards in the form

    #ifndef NEOVIM_FILENAME_H
    #define NEOVIM_FILENAME_H
        ...
    #endif /* NEOVIM_FILENAM_H */

* Renamed from *.pro -> *.h
* Moved from src/proto/ to src/

This would have caused conficts with some existing headers in src/;
rather than merge these conflicts now (which is a whole other can of
worms involving multiple and conditional inclusion), any header in src/
with a conflicting name was renamed from *.h -> *_defs.h (which may or
may not actually describe its purpose, the change is purely a
namespacing issue).

Once all of these changes were made a script was developed to determine
what #includes needed to be added to each source file to describe its
dependencies and allow it to compile; because the script is so short
and I'll just list it here:

    #! /bin/bash

    cd $(dirname $0)

    # Scrapes `make` output for provided error messages and outputs #includes
    # needed to resolve them.
    #   $1 : part of the clang error message between filename and identifier
    list_missing_includes() {
        for file_missing_pair in $(CC=clang make 2>&1 >/dev/null | sed -n "s/\/\(.*\.[hc]\).*$1.*'\(.*\)'.*/\1:\2/p"); do
            fields=(${file_missing_pair//:/ })
            source_file=${fields[0]}
            missing_func=${fields[1]}
            # Try to find the declaration of the missing function.
            echo $(basename $source_file) \
                \#include \"$(grep -r "\b$missing_func __ARGS" | sed -n "s/.*\/\(.*\)\:.*/\1/p")\"
        # Remove duplicates
        done | sort | uniq
    }

    echo "Finding missing function prototypes..."
    list_missing_includes "implicit declaration of function"
    echo "Finding missing identifier declarations..."
    list_missing_includes "use of undeclared identifier"

Each list of required headers was added by hand in the following format:

    #include "vim.h"
    #include "*_defs.h"
    #include "filename.h"
    /* All other includes in same module here, in alphabetical order. */
    /* All includes from other modules (e.g. "os/*.h") here in alphabetical
     * order. */

src/if_cscope.h

@@ -1,72 +1,16 @@
-/* vi:set ts=8 sts=4 sw=4:
- *
- * CSCOPE support for Vim added by Andy Kahn <kahn@zk3.dec.com>
- * Ported to Win32 by Sergey Khorev <sergey.khorev@gmail.com>
- *
- * The basic idea/structure of cscope for Vim was borrowed from Nvi.
- * There might be a few lines of code that look similar to what Nvi
- * has.  If this is a problem and requires inclusion of the annoying
- * BSD license, then sue me; I'm not worth much anyway.
- */
-
-
-#if defined(UNIX)
-# include <sys/types.h>         /* pid_t */
-# include <sys/stat.h>          /* dev_t, ino_t */
-#else
-#endif
-
-#define CSCOPE_SUCCESS          0
-#define CSCOPE_FAILURE          -1
-
-#define CSCOPE_DBFILE           "cscope.out"
-#define CSCOPE_PROMPT           ">> "
-
-/*
- * s 0name	Find this C symbol
- * g 1name	Find this definition
- * d 2name	Find functions called by this function
- * c 3name	Find functions calling this function
- * t 4string	find text string (cscope 12.9)
- * t 4name	Find assignments to (cscope 13.3)
- *   5pattern	change pattern -- NOT USED
- * e 6pattern	Find this egrep pattern
- * f 7name	Find this file
- * i 8name	Find files #including this file
- */
-
-typedef struct {
-  char *  name;
-  int (*func)__ARGS((exarg_T *eap));
-  char *  help;
-  char *  usage;
-  int cansplit;                 /* if supports splitting window */
-} cscmd_T;
-
-typedef struct csi {
-  char *          fname;        /* cscope db name */
-  char *          ppath;        /* path to prepend (the -P option) */
-  char *          flags;        /* additional cscope flags/options (e.g, -p2) */
-#if defined(UNIX)
-  pid_t pid;                    /* PID of the connected cscope process. */
-  dev_t st_dev;                 /* ID of dev containing cscope db */
-  ino_t st_ino;                 /* inode number of cscope db */
-#else
-#endif
-
-  FILE *          fr_fp;        /* from cscope: FILE. */
-  FILE *          to_fp;        /* to cscope: FILE. */
-} csinfo_T;
-
-typedef enum { Add, Find, Help, Kill, Reset, Show } csid_e;
-
-typedef enum {
-  Store,
-  Get,
-  Free,
-  Print
-} mcmd_e;
-
-
-
-/* the end */
+#ifndef NEOVIM_IF_CSCOPE_H
+#define NEOVIM_IF_CSCOPE_H
+/* if_cscope.c */
+char_u *get_cscope_name __ARGS((expand_T *xp, int idx));
+void set_context_in_cscope_cmd __ARGS((expand_T *xp, char_u *arg,
+                                       cmdidx_T cmdidx));
+void do_cscope __ARGS((exarg_T *eap));
+void do_scscope __ARGS((exarg_T *eap));
+void do_cstag __ARGS((exarg_T *eap));
+int cs_fgets __ARGS((char_u *buf, int size));
+void cs_free_tags __ARGS((void));
+void cs_print_tags __ARGS((void));
+int cs_connection __ARGS((int num, char_u *dbpath, char_u *ppath));
+void cs_end __ARGS((void));
+/* vim: set ft=c : */
+#endif /* NEOVIM_IF_CSCOPE_H */