Fixes for COBOL syntax highlighting and tag processing.

The following code changes re-enable syntax highlighting and clean up tag parsing for COBOL source files. Please note that since code folding only works in the current implementation of geany if the sequence number area is deleted and area A statements begin in column 2 I modified the tag parser to handle source files with that structure. I have been programming COBOL for more than 20 years and these mods work well with our various source code files.  This is my first attempt to supply patches using github.