Changed the low level type representation from a strung of unsigned short

Changed the low level type representation from a strung of unsigned short
elements to a string of structs, each representing one type element. This
should fix problems on unusual architectures, since it is no longer necessary
to embedd pointers and other data converted to numbers in the string of
unsigned shorts.
Increased the TypeCode length to unsigned long to make room for more type
bits.
Inline more functions in datatype.h.

git-svn-id: svn://svn.cc65.org/cc65/trunk@3709 b7a2c559-68d2-44c3-8de9-860c34a00d81