bump version, update NEWS, prepare to release 9.3

NEWS

+Version 9.3
+    - fix freezing main window on --row-action in list or @cmd in form dialogs
+
 Version 9.2
     - some fixes of menu in editable lists
     - add two additional item to menu in editable lists - "move up" and "move down"

configure.ac

-AC_INIT([YAD], [9.2], [https://github.com/v1cont/yad/issues/], yad, [https://github.com/v1cont/yad/])
+AC_INIT([YAD], [9.3], [https://github.com/v1cont/yad/issues/], yad, [https://github.com/v1cont/yad/])
 AC_CONFIG_AUX_DIR([build])
 
 AM_INIT_AUTOMAKE([1.11 foreign dist-xz no-dist-gzip])