Fix the duplicate header autoload keys
Fix Jira #ROOT-6188 TApplication in ROOT 6 under unix changes value of "optind" (from getopt)

The commented line of code is a TCint legacy and its purpose is not clear...
Fixed GenVector and Smatrix dictionaries using -multiDict option. Fixes ROOT-6325
Release notes update
Fix ROOT-6331: Properly handle protoclasses of hepmc

my commit but work of Axel :-)
Wrap using decl/def that are followed by code (ROOT-6153).