Remove regular-only implementation

[Yowgf]

The README documentation refers to the implementation that can generates a regular grammar for the text under analysis. Regular grammars are equivalent in power to a regular expression. It cannot, for instance, count balanced parenthesis pairs.

We should completely remove the regular-only implementation from the repository, and rename the context-sensitive implementation to become the "intuitive" one to use -- for anybody new to the repo, it should be the first one they want to use.