UTF32 is not implemented

Comment out code detection for UTF32 to avoid uninitialized var
Remove comparison between unsigned and zero

REBCNT is unsigned
Fix memory leak

Found by sanitize=address of GCC
Make local functions static
Add an env to always alloc memory from system pool

Might be helpful for debuging memory problems.
Fix a memory leak
Prefix all env with R3_
Rearrange structure members such that pointers are naturally aligned

This also prevents valgrind complaining memory leaks, because valgrind
only tries to find well-aligned pointers. (Those leaks become "still
reachable" now)

This commit also changes the way to access image dimensions from host
env: IMG_WIDE/HIGH defined in reb-series.h is used.

reb-series.h seems not to be used otherwise
Remove the extra element in the block when reducing a block

Make_Block will add space for the END, so only pass in the length of the
real data
Fix a memory leak in to-png

The output buffer in lodepng_encode is dynamically allocated.
Serial reading could return 0 bytes with no errors

No idea why this could happen though
Remove unused "index" field from REBREQ