Rewrote (static) gte_keys() function

This function called realloc in a loop, which was
a) bad
b) buggy

Now we have two loops instead, one of calculating the required memory
space size, the second (n^2 loop) filling it.
Made debug macros verbosity configurateable

Added zero as default value for all macro "calls", to be still able to
compile.
removed header include before module name is defined
Changed verbosity settings for debug macro calls

Stuff, the user should know goes to DEFAULT_VERBOSITY and
MORE_VERBOSITY,
debugging stuff which is only relevant to the developer goes above
(MUCH_VERBOSE, SCREAMING_VERBOSE).

Added headers to include const/verbosity.h
Merge branch 'add-use_verbosity' into prepare-v0.0.6-0
Added member value setter magic to convert to int/double
default verbosity should be DEFAULT_VERBOSITY
debug macros dont need to check for verbosity, as printing function does it
Set config-verbosity to zero (should be default)
Merge branch 'rework-printing_and_verbosity' into prepare-v0.0.6-0
added splint check including gitignore for generated files
added missing set of exit_code