Update program_documentation.txt

Add details about bugs with the spanning tree library
Update spTest.bb

removed unused function
Add several .gitignore files

It will prevent any further unnecessary commit.
Add predefined bin/ for Darwin
Update with changes added to master

Merge to avoid any conflict when this branch will be ready to merge
back to master
Merge branch 'master' of http://github.com/claytronics/oldbb into meld2