prepare release of 0.19
Added tag 0.19rc1 for changeset 4818f5b68eb4
Added tag 0.19 for changeset 48407fa3f3c9
changelog
minor code cleanup
always convert C integer values to 1/0 when testing them for their boolean value
fix compiler crash
improve constant folding for boolean expressions (and/or)
fix switch transform after changing boolean coercion of integer expressions
fix test result reporting
fix test in Py3
fix compiler crash on bad code (complex % x) and move directive handling in ModNode to analysis phase