STR-312 Implement failure by returning NULL (instead of setjmp/longjmp) 
STR-312 Implement failure by returning NULL (instead of setjmp/longjmp) 

Started conversion of s2c in s2c-ng, which is not yet used in tests or
compiler. Converting abstract syntax to concrete syntax at the same
time.


svn path=/trunk/StrategoXT/; revision=12406

Apanatshka/strategoxt,Apanatshka/strategoxt,metaborg/strategoxt,lichtemo/strategoxt,metaborg/strategoxt,Apanatshka/strategoxt,lichtemo/strategoxt,metaborg/strategoxt,Apanatshka/strategoxt,metaborg/strategoxt,metaborg/strategoxt,lichtemo/strategoxt,Apanatshka/strategoxt,lichtemo/strategoxt,lichtemo/strategoxt