leap: first implementation of LeapFinger, inspired from LeapMotion by thomas
Fix #1396 : Allow objects inheriting from list or tuple

A SimpleListAdapter doesn't accept objects inheriting form list or
tuple, because it checks directly the type.

Here, in place of testing the type of the object, we use isinstance.

Also provide a testcase
Context and Sandbox widget: preliminary tests to fully seperate global instances of Builder, Cache, etc. Right now, only Builder is tested.
sandbox: enhance sandbox separation, and add ExceptionManager into the sandbox management too.
sandbox: add a little comment for explaining the example
wip sandbox with clock
sandbox: ensure the container is created, and fix clock
Add profling recipe to App documentation.
Use sphinx syntax more effectively.
make sure  parameters aren't removed, @vak thanks for the fix
doc: revisions of modules/__init__.py
doc: revisions to modules/inspector.py
doc: revisions to modules/monitor.py
doc: revisions to modules/keybinding.py
doc: revisions to modules/recorder.py
screen: add nexus 7 (2012 and 2013 version) to screen module
changed up a very minor part in the scaling logic of
:meth:`Scatter.transform_with_touch`.
Merge branch 'master' into minor_code_fixes
refactored some constants so that they can be modified by the user.
refactored out the rounding of :attr:`DampedScrollEffect.value` when
coasting to stop to a new bool :attr:`round_value`.

But why does it need to be rounded in the first place?