Signed vs unsigned ints

[dengwirda]

Can unsigned ints be used everywhere? This would ease any signed-to-unsigned conversion issues, but -ve ints are currently used to denote certain flags... Would allow x 2 increase in max mesh size, but might increase size of in-mem. data-structures (to mark constrained faces, etc)?

Would be nice to compile quietly with -Wsigned-conversion -Wfloat-conversion -Wshadow and the equiv. with msvc, clang++, etc.