parser does not appear to accept inverted conditional if the argument is a constant as opposed to a parameter

[weatherhead99]

The following code appears to work:

param a=1
SEQUENCE test {
    if !a OtherTest();
RETURN;
}

SEQUENCE OtherTest {
RETURN;
}

however, the following appears not to

const a = 1
SEQUENCE test {
if !a OtherTest();
RETURN;
}
SEQUENCE OtherTest {
RETURN;
}

with the only difference being the use of "const" rather than "param" to defiune the parameter. These two constructs are the same in archon clocking language, so they should also both work in WDL. If it was intended that we never use the "constants" in archon and just stick to GPP predefs, fine, I'd be happy with a warning but it should still compile.