Fix segfault in parseCommand if no command name is found at end of file

Besides fixing the segfault, it assigns the `cmdProcessed` return value
properly.

Fixes: https://github.com/fishman/ctags/issues/72
Add unit test for vim commands
Merge branch 'fix-vim-segfault-empty-com-noline' of https://github.com/blueyed/ctags into blueyed-fix-vim-segfault-empty-com-noline
Merge branch 'blueyed-fix-vim-segfault-empty-com-noline' into deploy