add support for GNU Global

Thanks to
http://adam8157.info/blog/2014/11/use-gnu-global-for-source-code-tagging/
删除不再有用的 cscope 映射
spell update
cycle config update
use /var/tmp as backupdir too
don't use ~/temp as backupdir

normally such backup files are unimportant; important files have been
backed up already.
vimproc.vim: update
update filetype.vim for better httplog file detection
Merge branch 'master' into neocomplcache

Conflicts:
	autoload/vimproc.vim
	autoload/vimproc/cmd.vim
	autoload/vimproc/filepath.vim
	autoload/vimproc/parser.vim
	autoload/vimproc/util.vim
	doc/tags
	doc/vimproc.txt
	plugin/vimproc.vim