Update to 1.15

* Remove references to kpathsea xmalloc, and enable non-GNU malloc
* dvi.c: Fix long sleep interval in --follow
* Remove support for the now dead libt1
* special.c: Use <sys/wait.h>
* color.c: Fix segfault at missing xcolor.sty
* set.c: Added check for out of memory in libgd allocate
* ft.c: Add warning for missing target_light hinting
* dvipng.c: Use return value of fgets better

(markd)