Add libspeexdsp for CI

We are C++11

Fix case where resampler returns fewer samples than expected when filling final pad

Man, that "fgrep obsolescent" thing is annoying

Quality & performance improvements to built-in resampler following the lead of Rubber Band

Add speexdsp support

Remove libresample support, which hasn't been exercised in a long time

Shorten slightly to fit on a line

Always rebuild in bqvec, even if there is no similar Makefile - otherwise we might end up with a stale build or none at all

Use built-in resampler by default; add a Speex-specific Makefile; ensure platform tests run default Makefile last, so any output left in test/e2e/out is representative of the BQ resampler

Merge from branch resampler

Update docs to mention built-in implementation

Correct calculation of dot_length in multi-channel case, fixing buffer overrun

Add getEffectiveRatio

Fix overrun

Add reset

Refactor e2e tests, add another one

Copy ctor; some test material

Some minor debug/reporting improvements

Add quality option etc to example resampler