MacOs supports Png (edited gnuplot to allow png creation on a mac)
Added a function to plot multiple TMom hash tables on a single plot.
Extended TMom to also compute the mode value of the data.
Fixed bug in TMom standard error computaiton
Added a PlotValV function that also plots error bars/variances
added GetVal(), GetPrimHashCd() and GetSecHashCd() to TCnCom for Snap.py support
added another demo of connected components
applied a fix to mag.cpp from Myunghwan
removed a redundant declaration in mag.cpp
added conditional compilation for Snapworld
appended 'X' to the names of copy out scalar parameters in snap-core, which is needed for Snap.py
Use KeyId instead of NId for TNEANet attributes

Add{Int,Str,Flt}AttrDat[NE] use the NodeH.GetKeyId(NId) and
EdgeH.GetKeyId(EId) for their index into the attribute vectors, but the
rest of the functions did not. This would allow the functions to still
work if all the nodes corresponded exactly between the NId and the
KeyId, but this doesn't happen when you use LoadEdgeList.
More fixes and tests for TNEANet attributes

There were no checks that the right node was being set correctly which
allowed some errors in the attributes code to go unnoticed. Add in the
checks so that there is no regression.

These tests also found some more omissions from the last patch which are
also fixed.
Merge pull request #30 from kruton/master

Use KeyId instead of NId for TNEANet attributes
fixed a compilation warning in network.cpp
fixed a problem in TNEANet::DelEdge()
replaced aborts with exceptions for Snap.py, defined preprocessor switches for Snap.py, Snapworld, and backtrace conditional compilations, added g++ flags in Makefile
resolved compilation warnings
addressed a compilation warning on Mac OS X
Fixed infinite loop in TNEANet::DelEdge.