Changes mcb.LoadRegion and Region.Save to use a file name as
parameter. This is the more common use case.
Fixex mcbconv to reflect changes to mcb package.
Changes region file name in mcbconv to include 'r.' prefix.
A name like '-1.0.mcb' can cause problems when trying to use
it in unix command line programs. Some of them will interpret
-1.0.mcb as a switch, even when quoted.
Fixes some bugs in mcb package, which caused the reader
of region data to fail on byte arrays. Turns out that
r.Read(p) can do under-reads, leaving the buffer in
a wrong state. Changed r.Read(p) to io.ReadFull(r, p),
which fixed it.
Changed chunk coordinates from 8 bit to 16 bits in
mcbconv.
Continues work on mcmapgen.