Support to compile without debug messages

The ordinary user is usually not interested in debug messages, so they only make
the program bigger and slower for them.

The value of --enable-debug-messages (DEBUG_MESSAGES) defaults to the value of the
--enable-debug (DEBUG) setting. Of course it may be set individually to any value.
Fix object file extension on Windows

The default object file extension the OpenWatcom C/C++ compiler tools use on Windows
is .o, not .obj. Let's just stay with that...
Add a readme file for OpenWatcom users

Describing methods of building the software with the OpenWatcom C/C++ compiler.
Forgot to change it here...
Merge e-mail change fix
Silent library creation

Do not print librarian identification header lines, thus making the wmake output more readable.
Use command files instead of long command lines

Some systems have a very small limit on command line length, so let the OpenWatcom
tools use command files instead.
Fix wrong return value

When the file to read could not be opened, grffile_load() would return success
instead of failure. Though it doesn't really make a problem, since the returned
pointer is valid and points to a valid grffile_t, still it's better to indicate
failure properly.
Merge improvements specific to the OpenWatcom C/C++ compiler
Add copyright header to Makefile.am files
Count errors and add support for treating warnings as errors
Fix creating zero-length reference-counted strings.
Ignore error output files from the OpenWatcom C/C++ compiler
Merge fixes
Add common command line parser function

The parser handles internally the '--help' ('-h', '-?'), '--version' and '--verbose' ('-v')
options. Other options may be specified by the optdesc_t structure. Supports required
and optional arguments, integer and string values.