Fixed a spelling mistake
Correct improper base class function signature for toolcahinBase.find_libraries
Implemented FS#38

Libraries are now wrapped between -Wl,--start-group and -Wl,--end-group
blocks by default. This resolves link order issues and deals with
circular link dependencies. It can be disabled with
csbuild.Toolchain("gcc").EnableStrictOrdering()
Fix for FS#25 - Build hangs in bar_writer when exceptions are thrown

Additionally, removed the TODO items from the top of the file, as
they're now tracked in the bugtracker, and fixed an apparent whitespace
issue
Slightly more correct library search pattern.