Remove the concept of default platform from LbEnv
- BINARY_TAG/CMTCONFIG not set by default
- lb-run treats unset BINARY_TAG as "best"
- add support for
lb-run -c best Project/latest
- it picks up the latest version and try to see if any of the platforms are usable
- minor bugfixes
Note that some of the changes are coming from automatic formatting with YAPF.
Closes LBCORE-1859 and closes LBCORE-1860
Edited by Marco Clemencic