* HitCreateDrag::start_grab does not need to do anything
a hit cannot be past end of region. Drawing at or past
the end of a region will create a new region (not an event)
* HitCreateDrag::finished now calculates the position like
NoteCreateDrag::finished.
* the selection does not need to be cleared. Creating new
notes/hits selectes the newly created ones.
The old code could not snap to the grid, because it had a lot of confusion about pixels vs. time,
and between line-origin-relative time and absolute time
Despite what the docs say Gtk::HScale(0,1,s) with a step-size
s > 0 has a range [0, 1 - s]. GTKMM does allow for a step-size
of zero, which also works around this issue.
This works because gtkmm sidesteps gtk_hscale_new_with_range() which
would fail with g_return_val_if_fail (step != 0.0, NULL);
The reason for this is that gtkmm creates an Adjustment with a
page-size = step-size:
```
Adjustment* adjustment = manage(new Adjustment(min, min, max, step, 10 * step, step));
```
and `gtk_adjustment_configure` limits the range:
```
value = MIN (value, upper - page_size);
```
The state has to be pushed to the manager during initialization,
otherwise channel_config remains unset.
This fixes an issue with files using the same filename
(missing channel name) during stem export.
This is consistent, since after handling the
`SaveSessionRequested` signal the session remains dirty
(which may be a bug). However since the signal is handled
by the GUI, rec-stop only saves the session if there is a GUI.
It is however somewhat dangerous. Record, quit + no-save (or
changing snapshots w/o saving first) will loose any references
to the recorded data (even though it is still on disk).
Note that "remove last capture" still saves the session
(to prevent references to non-existent sources).
