volk: cleaned up 32fc_x2_dot_prod_32fc code. Improved results; fixed on OS X.

- Added unaligned versions of kernels.
- Fixed issues with tail handling
- Use _mm_setzero_ps instead of subtracting to zero out values
volk: fixed issue with size_t comparison of std::string function (compare against std::npos, not -1).
Merge branch 'maint'
qtgui: enables use of QWT 6.1.
Revert "GNU Radio EXPAND macros for template files:"

This reverts commit 6fc200fcba65cc4d18d7b10381da72769c0183c4.

The original commit causes excessive rebuild sensitivity by
regenerating many public API header files at cmake time instead
of at build time.
filter: fixed issue with resampler using buffer size information (always a mistake).

The intent was to ask the scheduler for the maximum amount of data. Now, it plays it safe by asking for just enough the next time. Performance tests show it works well.
qtgui: enables use of QWT 6.1.
Merge branch 'master' of git.gnuradio.org:gnuradio
Merge branch 'maint'