updated GalSim version to v0.4 in preparation for tagging
update to history, changelog files for new version
Disable the tests that time seed gives different answers from specific seed for Poisson (same problem as we had with BinomDist, but less common).
trim history somewhat, and make it and README consistently 80 char width rather than 100 we use for code.
added port files needed for those who want to install using Macports
put correct MacPorts installation instructions in INSTALL.md
Merge branch 'master' into #304