in order to harmonize with the Stdio.Stat API. Also includes compat.

The internal cache for compile_memsearcher() could grow very large before
the gc would clear some of its entries (each entry has a size of ~16KB).
It now has a dynamic threshold for when it clears the cache on its own.

This function is needed to perform some low-level modifications of mappings.

Contributed from Roxens commercial software.

Needed by Oracle module.

This made our usage of it about 20% faster.

This is done mainly by avoiding making (shorter) copies of the buffer
string when reading.

The object had only one data_ok function, now changed to have one per request.

The solar event calculations now compensate for the difference between
TDT (Terrestrial Dynamical Time) and UTC.

Also fixes some AutoDoc mk II markup bugs.

The calculations now seem to be reasonably accurate.

The function low_destruct_objects_to_destruct() is used
by the destruct_objects_to_destruct() macro, which may
be used by dynamic modules (eg Oracle).

The variable objects_to_destruct is used by the
destruct_objects_to_destruct() macro, which may
be used by dynamic modules (eg Oracle).

Oracle's jvm.dll has dependencies on runtime libraries that it doesn't
install in the global dll path or in the same directory. This patch
adds the directory where they do install the required dlls to the dll
search path, with a fallback to using the current directory on older NT.

The main change in this patch is to fix some calling-convention bugs in
earlier attempts, and to use the Unicode APIs.