Merge pull request #75 from arthurbenemann/issue48

There are some big modifications to the structure on 0d7412f , so I`m pulling this to master even if it the work on #48 is not finished.
Merge branch 'issue48' into master add the modificatons in the release v0.7.2
Preparing for release v0.7.2
Merge branch 'issue48'
To get the new TTS messages in master.
Refactoring the seekbar widget to a new object.

So it can be reused in other parts of the program
Moving the select altitude Dialog to a new class. Using a seek bar to select the altitude.
Change the Altitude Dialog to use a numberPicker.
Moving drone pointer to the SuperActivity.
Using an interface for the altitudePicker callback.
Moving changeDefaultAlt() to the SuperActivity.
Using the AltitudeDialog to set guided mode altitude.

This Closes #77.
Merge pull request #78 from arthurbenemann/issue77

Issue #77
Better dialog for setting the default heigh.
Guided mode uses the default heigh.
Refactoring the seekbar Widget.
Adding remaning battery indication.
Fix one more item for issue #41.
Merge pull request #79 from arthurbenemann/issue41

Adding remaning battery indication.
Preparing for release v0.7.3
.tlog files are now compatible with Mission Planner
Merge pull request #80 from arthurbenemann/issue57

.tlog files are now compatible with Mission Planner
Preparing for release v0.7.4