-- instead of looking at major and minor, we'll do what the ack completion
module does: produce an x.y version number that we then compare directly to,
to avoid complicated "if major version OR minor version" checking
* Guard both ack & ag from completing if command doesn't exist.
* Allow some opts to repeat like ignore.
* Update descriptions.
* Ack was missing some opts present in base 2.00.
* Ag cleanup based on better understanding.
* Simplified parsing of filetypes, no more awk-fu!
* Added version based checks to complete only existing features
* Added missing opt --passthrough
* Lowercased all strings not 2 sentences