This change adds a new command line option `qmake` to the tool which
allows the user to specify the qmake executable to be used. By default,
if that option is omitted, the behavior is unchanged (i.e. the tool first
searches for the `qmake` executable and - if this is not successful -
then for either `qmake-qt5` or `qmake-qt4`. If the new option is used,
no search takes place and instead the executable provided is used as-is.
This implements a part of the functionality as discussed in issue #94.
Martin Höher
a3a6376573