Require sphinx >1.4 for sphinx extension imgmath
Require sphinx >1.4 for sphinx extension imgmath

It looks like an up-to-date local sphinx build suggests to use imgmath, but RTD uses sphinx 1.3.5, which is a major version behind 1.4, where imgmath was introduced. If we require sphinx >1.4 in the rtd docbuild, the build should find sphinx.ext.imgmath.
sjsrey/pysal_core,ljwolf/pysal_core,pysal/pysal,hasecbinusr/pysal,sjsrey/pysal_core,pedrovma/pysal,ljwolf/pysal_core,lixun910/pysal,lixun910/pysal,hasecbinusr/pysal,hasecbinusr/pysal,sjsrey/pysal_core,TaylorOshan/pysal,lixun910/pysal,ljwolf/pysal,sjsrey/pysal,TaylorOshan/pysal,ljwolf/pysal,weikang9009/pysal,TaylorOshan/pysal,ljwolf/pysal,ljwolf/pysal_core,lanselin/pysal