Working on new trace API
Adapting fec stacks to new trace api

* Still a number of todo's to be fixed but code compiles and tests run
merge with master
removed obsolete unit tests and moved tests to correctly named test files
implement test for test_trace_decode and fix style
added test for trace_layer
started working on unit test for trace_set_symbol_storage, stopped uing std::to_string
added comment about resetting callback function
almost done with trace set symbol storage unit tests
merge
finish unit test for trace_set_symbol_storage
fix todos
address comments
removed todo
minor fix
Merge pull request #127 from steinwurf/modify-trace-api

Modify trace api
Preparing to create tag 20.0.0
Merge remote-tracking branch 'remotes/origin/master' into add-perpetual-code
Add new trace layer