linear: moved vec4 comparison operators to the interface header.
hash: redesigned interface; added hash combiners.

hash:
	made functional interface generic;
	replaced hash-specific functions with implementation aliases;
	added generic_combiner.

hash/fnv:
	added stateful hashing to FNV hashing algorithms;
	replaced <algorithm> & lambda use in FNV algorithms with for loops;
	added combiner aliases.
test/hash: updated to new hash interface.
test/hash/combiner: new test.
test/premake: added .elf suffix for Linux.

test/.gitignore: replaced test-specific exclusions with *.elf
test: removed unused clean_binaries.sh.
hash: doc tidy.