Improve parser to support free cobol
Merged 'develop'.
Remove QTreeWidgetItem inheritance for AST nodes

A utitlty function is used to make the mapping

Also add var description to CC tooltip
Add support for File Definition statement
Ignore bin dir (for test files)
Refactor

Rename parse into parse_ast

Improve parser
Add parser test suite
Merge pull request #20 from OpenCobolIDE/feature/free⁻parser

Finish free parser