Update CharView after changing anchor type or ligature index

Just like other operation of Anchor Point Info dialog.
In gutils/gimagereadxpm.c, input file is text, not binary - fixed oops!
In gutils/gimagereadxpm.c, exit on file read error. Added more commenting
In gutils/gimagereadxpm.c, cleanup exit on file errors to common goto loc
In gutils/gimagereadxpm.c:gww_getline, exit on file error or buf overflow
In gutils/gimagereadxpm.c:gww_getstring, exit on file err or buf overflow
In gutils/gimagereadxpm.c:gww_getstring, exit if not enough memory
In gutils/gimagereadxpm.c:gww_getstring, replace galloc and cleanup on exit
In gutils/gimagereadxpm.c:gww_getstring, no segfault on freetab()
In gutils/gimagereadxpm.c, cleanup and exit if not enough memory.
In gutils/gimagereadxpm.c, if any errors encountered, cleanup and exit.
Merge pull request #530 from JoesCat/master

gutils/gimagereadxpm.c test for errors and cleanup