Generate separate text files for every language

The C code generator of textres2compiler now generates
separate C source (implementation) files for every language.

The generated files are now stored in the directory
"C-kern/resource/generated/".
Add define of standard value OFF_MAX

OFF_MAX declares the maximim value of the file offset
type off_t.
Change implementation isfree_memblock

The function isfree_memblock now returns true
only if addr and size are both set to 0.
The former implementation checked only the value of addr.
Change DNS IDN ACE encoding test

unittest_io_ipaddr():

The encoding test now uses "www.wörterbuch.de" instead of "www.café.com".
The corresponding ACE encoding is "www.xn--wrterbuch-07a.de".
Rename grow_memblock into growleft_memblock

The function shrink_memblock is also renamed into
shrinkleft_memblock.

Two new functions were added:
shrinkright_memblock and
growright_memblock.

The "left" functions change the addr and size of memblock_t.
The "right" functions change only its size.