[CMakeLists] add -Werror to debug config cflags
[kmutil] revamp error handling & misc fixes
[kmzfile] revamp err handling & better comments
!BAD! half done kmseq -- commting to merge stash
[kmstr] update with semi-stable api & some docs
[kmutil] semi-stable api, fix const-ness

also a new type to describe file access modes
[kmseqfile] add initial version of seqfile
[test/data]add plain text test file & gz'd verison
[test.c] tidy test env setup, add new test files
[testdata.h] remove static chars from testdata
[test_util] fix util module tests w/ new api
[tests.h] define test errhandlers in tests.h