some things on platforms where 'just char' means unsigned char. Fix lots of
new signedness warnings resulting from that fix (which would have cropped
up on unsigned char platforms anyway). Also implement a small subset of
stdint.h for windows platform in frame.h, hope this does not create any
conflicts. This allows us to use types like uint64_t where relevant.
git-svn-id: svn+ssh://svn.gna.org/svn/warzone/trunk@569 4a71c877-e1ca-e34f-864e-861f7616d084