Implement

This is the first step towards taking Tabv from being a tiny hack and making it a legitimate plugin!
Make Tabcxxv command configurable

This is the first step moving Tabv away from being a tiny, embarassing
hack toward beingn a legitimate plugin.
+ Use a function to implement the Tabcxxv command
+ Use global variables to make it configurable
Same improvements as last commit, for Tabjsv
Extracted duplicate code into methods
Added standard Vim .gitignore file
Only open a new tab if the current buffer is named or non-empty

I have desired this feature for a long time. Not sure why I didn't
implement it before now.
Allow suffixing of Tabcxxv argument with <>

This indicates a generic class, and generic classes do not have source
files, only headers. Thus, it will only open the header and the unit
tests. This technique can be used, however, regardless of whether the
class is actually generic.
Began to update README for recent enhancements