parser: refactor to allow for easier testing
add compare test rig
allow for url overrides in package functions
remove extglob before sourcing PKGBUILDs

makepkg does this to deal with a bug in bash when encountering
semi-valid function names, e.g. package_libxml++.
reflection: sanitize whitespace when writing strings
parser: make sense of parser failures
put some lipstick on the compare rig
reflection: truly treat function vars as overrides