[xtend][IDEA] Added TokenSourceProvider to create a token source base on
a text, reader or stream; customized PsiAntlrGrammarGenerator for Xtend
to use flexer's token names

Change-Id: I8e67c36813892c58eaab3f590ea4e057f841d61a
Signed-off-by: akosyakov <anton.kosyakov@itemis.de>
Merge "[xtend][IDEA] Added TokenSourceProvider to create a token source base on a text, reader or stream; customized PsiAntlrGrammarGenerator for Xtend to use flexer's token names"
[resource] fixed regression introduced by
af3a63291ae372ef6623346bf21a52ddcbdd65c7
"avoid derived state calculation when unloading a resource" 
https://bugs.eclipse.org/bugs/show_bug.cgi?id=451668
Merge "[resource] fixed regression introduced by af3a63291ae372ef6623346bf21a52ddcbdd65c7 "avoid derived state calculation when unloading a resource"  https://bugs.eclipse.org/bugs/show_bug.cgi?id=451668"