During generational collection, a userdatum must become gray and
go to a gray list after being traversed (like tables), so that
'correctgraylist' can handle it to its next stage.
This commit also added minimum tests for the generational collector,
including one that would detect this bug.
When creating code for a jump on a 'not' condition, the code generator
was removing an instruction (the OP_NOT) without adjusting its
corresponding line information.
This fix also added tests for this case and extra functionality in
the test library to debug line info. structures.
Roberto Ierusalimschy