remove AX_CHECK_ENABLE_DEBUG

it caused compilation to be done without -O2
only enable "timeit" if macro TIMEIT is defined
features.c: correctly report mmap availability
fix memleak in extract_uniques()
fixed three tiny memleaks
Bump version to 1.0.2, update NEWS & README
build `gen_ct` with AM_CPPFLAGS and AM_CFLAGS
always use threshold level 0 in short read mode
Merge branch 'master' into makedb_strictness