Add routines to set the personal file directory paths (personal

Add routines to set the personal file directory paths (personal
configuration file directory and directory in which to save captures),
have the routine to parse -P options use them, and move that routine to
libui.

Have that routine just return a gboolean.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@53435 f5534014-38df-0310-8fa8-9805f1628bb7