oleaut: Rename SLTG_DoType to SLTG_DoElem and split out the common TYPEDESC generating code to SLTG_DoType.

Process SLTG alias types with SLTG_DoType as the data is stored in the
same format as in other components of the typelib.

common to all elements, so move the processing of these from the
individual element processing.

Improve SLTG alias processing.

either set or not set (reported by Andrey Turkin).

match those of ReadProcessMemory/WriteProcessMemory, since those are
the ones actually used.

the exponent parsing to after the hex digit parsing.