+ fix several warnings from clang 3.1 --analyze, includes correcting
a null-pointer check in _nc_mvcur_resume.
+ correct display of double-width characters with MinGW port (report
by Erwin Waterlander).
+ replace MinGW's wcrtomb(), fixing a problem with _nc_viscbuf
> fixes based on Coverity report:
+ correct coloring in test/bs.c
+ correct check for 8-bit value in _nc_insert_ch().
+ remove dead code in progs/tset.c, test/linedata.h
+ add null-pointer checks in lib_tracemse.c, panel.priv.h, and some
test-programs.