Remove hardcoded lists of int and float types.
Remove hardcoded lists of int and float types.

We can use `type.GetTypeFlags()` and then check lldb.eTypeIsInteger,
lldb.eTypeIsFloat, etc. This also fixes a problem where C++ `bool`s
weren't properly converted to python `bool`s: they are recognized as
integers now in both `Value._as_number` and `Value.__bool__`.

sivachandra/gala,sivachandra/gala