Update wxWidgets.
Refresh catalog manager after deleting a folder.

Not doing so was scary: it looked like some other project's items
disappeared.
Remove another forgotten bit of OS X in automake build.
Use 'make dist' to package sources.

Don't use the homegrown, outdated, broken scripts. This means the
sources tarball is only good for use on Unix, but that's OK, the other
builds require git submodules anyway and are better built directly from
git.

Various related updates to automakes to make it work.
Change version to 1.6, update NEWS.
Fix another welcome screen crash.
Fix LanguageCtrl hints on wxMSW.

The change in 30d1adb broke wxMSW for a change.