Remove many false positives from the ctags results

Anchoring the keyword as the first non-whitespace on a line may mean
that the occasional genuine-but-unconventionally-formatted tag is
missed, but it avoids a large number of false positives.

I changed the type descriptive texts about a bit too. That part's purely
cosmetic.

I also changed the ignored file list to use a filename matching the make
rule, `TAGS.vi` instead of `TAGS.vim`.

.gitignore

@@ -52,7 +52,7 @@
 lexer.ml
 TAGS
 TAGS.emacs
-TAGS.vim
+TAGS.vi
 version.ml
 version.texi
 /Makefile

src/etc/ctags.rust

@@ -1,11 +1,12 @@
---langdef=rust
---langmap=rust:.rs
---regex-rust=/[ \t]*fn[ \t]+([a-zA-Z0-9_]+)/\1/f,function/
---regex-rust=/[ \t]*type[ \t]+([a-zA-Z0-9_]+)/\1/T,types/
---regex-rust=/[ \t]*enum[ \t]+([a-zA-Z0-9_]+)/\1/T,types/
---regex-rust=/[ \t]*struct[ \t]+([a-zA-Z0-9_]+)/\1/m,types/
---regex-rust=/[ \t]*mod[ \t]+([a-zA-Z0-9_]+)/\1/m,modules/
---regex-rust=/[ \t]*static[ \t]+([a-zA-Z0-9_]+)/\1/m,consts/
---regex-rust=/[ \t]*trait[ \t]+([a-zA-Z0-9_]+)/\1/m,traits/
---regex-rust=/[ \t]*impl[ \t]+([a-zA-Z0-9_]+)/\1/m,impls/
---regex-rust=/[ \t]*macro_rules![ \t]+([a-zA-Z0-9_]+)/\1/m,macros/
+--langdef=Rust
+--langmap=Rust:.rs
+--regex-Rust=/^[ \t]*(pub[ \t]+)?fn[ \t]+([a-zA-Z0-9_]+)/\2/f,functions,function definitions/
+--regex-Rust=/^[ \t]*(pub[ \t]+)?type[ \t]+([a-zA-Z0-9_]+)/\2/T,types,type definitions/
+--regex-Rust=/^[ \t]*(pub[ \t]+)?enum[ \t]+([a-zA-Z0-9_]+)/\2/g,enum,enumeration names/
+--regex-Rust=/^[ \t]*(pub[ \t]+)?enum[ \t]+([a-zA-Z0-9_]+)/\2/g,enum,enumeration names/
+--regex-Rust=/^[ \t]*(pub[ \t]+)?struct[ \t]+([a-zA-Z0-9_]+)/\2/s,structure names/
+--regex-Rust=/^[ \t]*(pub[ \t]+)?mod[ \t]+([a-zA-Z0-9_]+)/\2/m,modules,module names/
+--regex-Rust=/^[ \t]*(pub[ \t]+)?static[ \t]+([a-zA-Z0-9_]+)/\2/c,consts,static constants/
+--regex-Rust=/^[ \t]*(pub[ \t]+)?trait[ \t]+([a-zA-Z0-9_]+)/\2/t,traits,traits/
+--regex-Rust=/^[ \t]*(pub[ \t]+)?impl([ \t\n]+<.*>)?[ \t]+([a-zA-Z0-9_]+)/\3/i,impls,trait implementations/
+--regex-Rust=/^[ \t]*macro_rules![ \t]+([a-zA-Z0-9_]+)/\2/d,macros,macro definitions/