Handle "-.3"
Add two unit tests for Lexer_getNumber:
 - check that it handles PostScript numbers correctly (should be able to parse '-.002', '34.5', '-3.62', '123.6e10', '1E-5', '-1.', '0.0', '123', '-98', '43445', '0' and '+17')
 - check that it doesn't consume too many characters (in order to be able to parse glued numbers and operators)
Handle PostScript numbers correctly
Don't consume too many characters
Style corrections