perf(sources): simplify codebase, make tests 83% faster (32s -> 5.3s) in sources, 99.5% faster for TickSource tests (29s -> 0.13s), feeder package in 126s.

perf(sources): simplify codebase, make tests 83% faster (32s -> 5.3s) in sources, 99.5% faster for TickSource tests (29s -> 0.13s), feeder package in 126s. #74