Rename completion function and plugin file

Change plugin file to tmuxcomplete.vim
Change function name to tmuxcomplete#complete
CompleteScript still delegates to new function
Return matches as list instead of complete_add
Move tmuxcomplete#complete to autoload
Use POSIX compliant single brackets in sh/tmuxwords.sh
Merge pull request #24 from wellle/single-brackets

Use POSIX compliant single brackets in sh/tmuxwords.sh
Merge pull request #22 from ferreum/rename-func

Rename completion function and file, return results as list
Remove function CompleteScript and cpoptions
Merge pull request #25 from wellle/remove-function

Remove function CompleteScript and cpoptions