Refactor application packaging for linux/macos. (#310)

Refactor application packaging for linux/macos. (#310)

* Refactor application packaging for linux/macos.

Packaging of the GUI for linux/macos can now be done
either by building the make target "package" created by
"qmake app.pro", or by executing a bash script "package_app".
Packaging with the legacy configure flow will build the
package target.
Travis CI scripts will build the package target.

The obsolete script mac-localize is deleted.  This
functionality is included in package_app.

The obsolete script makelinuxdist.sh is deleted.  We have not
distributed a linux package in some time.  Furthermore this
scirpt hadn't worked in some time.  package_app does not
create a standalone linux app, however it packages all the
bits from GPSBabel in GPSBabelFE.  This makes creating a
Docker app, which includes the Qt installation, for GPSBabel easy.

Merge relevant Qt .qm files into one qt_xx.qm file for each language
as recommended by Qt.
Deploy these meged .qm files with linux/macos builds.
Since Qt5 we only deployed the meta catalog, but not it's
dependencies. This should have led to the dependencies not
being available without Qt being installed.

gpsbabel.qm and gpsbabelfe.qm are no longer included in the packaged
apps for windows/linux/macos, as it should be.