Add automatic generation of headers

- The 'stripdecls.py' script replaces declarations in all headers by includes to
  generated headers.
  `ag '#\s*if(?!ndef NEOVIM_).*((?!#\s*endif).*\n)*#ifdef INCLUDE_GENERATED'`
  was used for this.
- Add and integrate gendeclarations.lua into the build system to generate the
  required includes.
- Add -Wno-unused-function
- Made a bunch of old-style definitions ANSI

This adds a requirement: all type and structure definitions must be present
before INCLUDE_GENERATED_DECLARATIONS-protected include.

Warning: mch_expandpath (path.h.generated.h) was moved manually. So far it is
the only exception.

src/nvim/ops.h

@@ -4,63 +4,9 @@
 #include "nvim/func_attr.h"
 #include "nvim/types.h"
 
-/* ops.c */
-int get_op_type(int char1, int char2);
-int op_on_lines(int op);
-int get_op_char(int optype);
-int get_extra_op_char(int optype);
-void op_shift(oparg_T *oap, int curs_top, int amount);
-void shift_line(int left, int round, int amount, int call_changed_bytes);
-void op_reindent(oparg_T *oap, int (*how)(void));
-int get_expr_register(void);
-void set_expr_line(char_u *new_line);
-char_u *get_expr_line(void);
-char_u *get_expr_line_src(void);
-int valid_yank_reg(int regname, int writing);
-void get_yank_register(int regname, int writing);
-void *get_register(int name, int copy) FUNC_ATTR_NONNULL_RET;
-void put_register(int name, void *reg);
-int yank_register_mline(int regname);
-int do_record(int c);
-int do_execreg(int regname, int colon, int addcr, int silent);
-int insert_reg(int regname, int literally);
-int get_spec_reg(int regname, char_u **argp, int *allocated, int errmsg);
-int cmdline_paste_reg(int regname, int literally, int remcr);
-int op_delete(oparg_T *oap);
-int op_replace(oparg_T *oap, int c);
-void op_tilde(oparg_T *oap);
-int swapchar(int op_type, pos_T *pos);
-void op_insert(oparg_T *oap, long count1);
-int op_change(oparg_T *oap);
-void init_yank(void);
-void clear_registers(void);
-int op_yank(oparg_T *oap, int deleting, int mess);
-void do_put(int regname, int dir, long count, int flags);
-void adjust_cursor_eol(void);
-int preprocs_left(void);
-int get_register_name(int num);
-void ex_display(exarg_T *eap);
-int do_join(long count,
-            int insert_space,
-            int save_undo,
-            int use_formatoptions,
-            bool setmark);
-void op_format(oparg_T *oap, int keep_cursor);
-void op_formatexpr(oparg_T *oap);
-int fex_format(linenr_T lnum, long count, int c);
-void format_lines(linenr_T line_count, int avoid_fex);
-int paragraph_start(linenr_T lnum);
-int do_addsub(int command, linenr_T Prenum1);
-int read_viminfo_register(vir_T *virp, int force);
-void write_viminfo_registers(FILE *fp);
-char_u get_reg_type(int regname, long *reglen);
-char_u *get_reg_contents(int regname, int allowexpr, int expr_src);
-void write_reg_contents(int name, char_u *str, int maxlen,
-                        int must_append);
-void write_reg_contents_ex(int name, char_u *str, int maxlen,
-                           int must_append, int yank_type,
-                           long block_len);
-void clear_oparg(oparg_T *oap);
-void cursor_pos_info(void);
+typedef int (*Indenter)(void);
 
-#endif /* NVIM_OPS_H */
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "ops.h.generated.h"
+#endif
+#endif  // NVIM_OPS_H