all types of build.
CMake builds use 'svn info' (the git-svn equivalent is also supported)
to get the real latest revision of the workspace that is used to
source a build. If the sources are not in VCS workspace (build from
source snapshot archive for example) then the $Rev$ svn keyword
expansion in mainwindow.cpp is used despite its issues with accuracy.
Non-CMake builds use the $Rev$ keyword expansion where possible.
If a CMake build is from a VCS workspace with local modifications; a
'-dirty' suffix is added to the revision number to denote that.
If no revision number information can be found the word 'local' is
used as a revision number.
The revision specification is used in the WSJT-X "about" box and is
sent to PSKReporter.info as part of the local station information
(this can be viewed at the statistics page
http://pskreporter.info/cgi-bin/pskstats.pl).
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@4017 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
