Updating RC file format

I have fixed the condition of when a block is of the language that specified and must included. Now one line comments are also detected and ignored, also I have added TEXTINCLUDE blocks to be ignored (they are for Visual Studio Editors).

For the test part, I have added the method `test_parse` to `test_rc` file. It create a temporary file (and folder) with a little test rc file, load it and then check if strings are correctly extracted.