Add in support for vxl.
Add Breathe package
FFTW: build single precision as well
Add nanomsg.
Add flask + dependencies.
Merge pull request #198 from lanewittgen/master

flask and nanomsg
Merge pull request #196 from hashdist/fftw

FFTW: build single precision as well
Add in a test to verify that vxl builds correctly.
Merge pull request #156 from robertmaynard/vxl_pkg

Add in support for vxl.
add folium
Merge pull request #199 from hashdist/add_folium

add folium
Merge pull request #193 from hashdist/breathe

Add Breathe package
Update PCRE, enable more options
Merge pull request #202 from hashdist/pcre

Update PCRE, enable more options
Add Julia package

This version uses Hashdist's LLVM, otherwise builds everything else itself.
Reuse our openblas, FFTW, GMP and MPFR