Move thread.c/process.c into subdir task/

threadpool.c is also moved into directory "C-kern/platform/shared/task/

Also corrected some comments in waitlist.h
Add support for string table in textrescompiler

The textresource_compiler now supports the generation
of a string table which lists all text resources.

Conditional text and parameter values are not supported
in case of string table generation.

The version of the new resource format is "3".

A test table "C-kern/resource/errtab.text" is added to the resource
section which describes the new format.
Adapt tool generrtab to generate textresource

Generrtab was changed to write its output in a form
which is is understood by the textresource_compiler.

It writes its output also in two languages.
The language defined in the user environment (which
is German in my case) and the default language of the
C environment (which is English).