tree dumping goes to stderr
added some optional debug printing
added explicit support for some more types

- boolean constant
- long long double (as void)
- variable-length array (assuming len 0)
- union (as void)
- empty compile units
debug-printing via complain()
style changes

- no spaces in ()
- hanging braces
- no camelCase
- collapsed long lines
sq with whitespace
a bit more debug printing
added a disabled stub for complex float support
reworked attr_numeric() to report failures

This whole file is thus copyright me
enums are no longer assumed to have type 'int'
I now import functions using their linkage name

This is required for C++ methods