Add cppcheck_report.txt and *Dict.C to .gitignore
Add 'scons checkheaders=1' capability

Checks for existence of appropriate system header files in configure
step.
Add 'scons srcdist=1' capability
Fix bug in THaGenDetTest.h - did not include <iostream>

Only revealed in compiling standalone codes.
Merge remote-tracking branch 'upstream/master' into softlink

Conflicts:
	SConstruct.py
	darwin64.py
	linux32.py
	linux64.py