Added class TExogamSpectra and modified TExogamPhysics for Exogam online spectra
Merge branch 'NPTool.dev.prerelease' of https://github.com/adrien-matta/nptool into NPTool.dev.prerelease

Conflicts:
	NPLib/Exogam/TExogamPhysics.cxx
Merge branch 'NPTool.dev.prerelease' of https://github.com/adrien-matta/nptool into NPTool.dev.prerelease

Conflicts:
	NPLib/Exogam/TExogamPhysics.cxx
	NPLib/Exogam/TExogamSpectra.cxx