Simplified placing of cursors:

- allow a cursor to be set by using CTRL/CMD + double click;
- add a preference settings to make placing a cursor the default
  when double clicking in the view;
- simplified the propagation of cursor changes using events.
Restored the measurement mode:

- provide easy access to timing information by hovering the mouse
  over the waveforms;
- added support to freeze a measurement temporarily in order to
  verify data or something;
- restored the snap cursor mode functionality.
Fixed some small issues in the pulse count view.
Several bugfixes and improvements:

- restored the toolbar functionality;
- made open/save actions generic;
- some typo's fixed.
Further work on improving the client:

- updated the icon set to the latest Gnome icon theme;
- added some small icons for use in view toolbars;
- restored the project load/save functionality;
- simplified the tools that create new AcquisitionData instances by
  hiding the publishing of this data to the base tool dialog;
- made a generic save/save-as action;
- fixed some small bugs.
Fixed failing junit.