Project skeleton. Has a parser library, a test case and a README.md file.
Add resource with sample org files.

Add SimpleTree.org as a first example fir parsing.
Add OrgMode::Parser class.
Begin parsing code. Add Exception class.
Ok, we can parse the first example file in tst_ParserTests.cpp.
Introduce OrgElement.

It is needed to parse multi-file agendas and to implement filters.
Keep the structure of the OrgFile represented for filtering.

(Squash it, the rcursion is broken).