blocks: split blocks swig into 3 files to be swigged individually.

Cuts down on memory footprint of swig. Using blocks_swig.py.in to pull them all in to one file afterwards.
filter: fixed pfb_arb_resampler to handle default taps (None) case.
Merge branch 'maint'
Merge remote-tracking branch 'arya/master_swig_split'
docs: don't depend on generated files from disabled components.
blocks: removing old blocks_swig.i file.
digital: fixes for SNR ests.

set_history: you keep using that word. I do not think it means what you think it means.
Merge branch 'maint'
docs: adds protection from generated files of components not configured.

Also removes a couple warnings in generating docs.