Update .gitignore.
Update .gitignore.

Ignores a subdirectory 'tdpl' in /tests,
as I'm currently playing around with things
related to the TDPL examples and SDC.

JohanEngelen/SDC,UplinkCoder/SDC,DmitryOlshansky/SDC,sidmutha/SDC,UplinkCoder/SDC,SDC-Developers/SDC,JohanEngelen/SDC,schancel/SDC,SDC-Developers/SDC,schancel/SDC,SDC-Developers/SDC,deadalnix/SDC,bpr/SDC,UplinkCoder/SDC,bpr/SDC,DmitryOlshansky/SDC,JohanEngelen/SDC,bpr/SDC,deadalnix/SDC,sidmutha/SDC,sidmutha/SDC,deadalnix/SDC,DmitryOlshansky/SDC,schancel/SDC