explicitly set VALID_ARCHs

while this doesn't seem to be needed in Xcode,
building from the command-line setting the
arch to i386 fails without mentioning i386 in
VALID_ARCHS
don't overwrite the deployment target in the project file
fix {NS,UI}LineBreakMode deprecation warnings
fix present/dismissModalViewController deprecationWarnings
add application tests & command line compatibility

* add application tests via the sample app
* add separate schemes for the logic+application tests that
 have the test target in the run phase
* add a Makefile to keep track of how to run the tests
Readme: extended the ARC notice, fixed subclassing notice

closes pull #198
Fixed typo in sample app
don't stack popover controllers

* store a reference to the currently shown popover controller
* dismiss it when the view disappears
* dismiss and return if the 'show popover-button' is hit again

fixes #200
Sample app: fixed tableView background color in Settings tab