STR-353: refining check for overlapping left-hand sides
STR-353: refining check for overlapping left-hand sides

svn path=/trunk/StrategoXT/; revision=11819

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