Create "tex.vim"

Shortcuts to insert gather/equation environments.
Modify "ftplugin/tex.vim"

Add ":B" for inserting environments.
Add shortcuts in "ftplugin/tex.vim"

Add (),[],{}.
Modify "ftplugin/tex.vim"

Add shortcuts (( [[ {{ <<.
Merge branch 'master' of github.com:guudwu1986/vimrc

Conflicts:
	ftplugin/tex.vim