[ign] Help tags
[fix] match_words value is modified after being cached for next iteration

The script saves the value of match_words as s:match_words, caching it
to avoid extra work the next time the script is called. However, match
words was being modified (by appending the escaped value of the
'matchpairs' option) after the caching occurred. Thus, the cache was
dirty but not recognized as such, and the wrong match_words value was
then used on subsequent invocations.

Bug fixed by moving all match_words modifications before cache is
created or checked.
[fix] 'matchpairs' option value not taken into account when executing `]%` & `[%` mappings
update readme
Copy updated regexes from base vim repo

Conflicts:
	plugin/matchit.vim
Replace tabs with spaces
Enable support for user-configurable mappings
Add check for vim version
Fix textobject plug mapping name
Refine README.md

1. 将链接从 'exvim/ex-matchit' 改为 'Firef0x/matchit'
2. 更新 Vundle 一节，以 'Plugin' 取代 'Bundle'
3. 去掉所有行末空格