closes#291
This changes the error message "return value ignored" to "expression value is ignored".
This is because this error also applies to {1;}, which has no function calls.
Also fix ignored expression values in std and test.
This caught a bug in debug.readAllocBytes where an early Eof error would have been missed.
See #219.
if you try to use them on an external variable or function
then you get a compile error, since the alignment/section
is set externally in this case.
closes#244
Andrew Kelley
Josh Wolfe