improve output of 3rdparty build scripts
pin base SDK at 6.1 instead of using latest SDK

in Xcode 5 the „latest SDK“ would select base SDK 7.0, but we don’t
support that yet
remove shell script phase from unit test target

in Xcode versions prior to Xcode 5 it was necessary to have a shell
script phase for the unit test target that would execute the RunUnitTest
shell script; this shell script represented the unit test runner.

in Xcode 5, the RunUnitTest shell script is present, but it generates
an error saying „RunUnitTests is obsolete. To run unit tests for your
target, use the Test scheme action in the Xcode IDE and the test action
in xcodebuild.“

as a first step to make unit tests run again in Xcode 5, the shell
script phase is therefore removed from the unit test target.
remove Fuego and Boost dependency from unit test target

when running unit tests in Xcode 5 with the Fuego and Boost dependencies
active, there is a crash inside the Boost libraries at some point when
Boost attempts to destroy an exception object.

the reason for the problem is unknown. since I lack the time and the
inclination to deal with the issue, I decided to simply remove the
Fuego and Boost dependency from the unit test target.
execute unit tests when the „Test“ action is selected in Xcode (Cmd+U)

in Xcode 4 the unit test target had a shell script phase that made the
target runnable, i.e. it was possible to include the unit test target in
the „Run“ action of the main target. as a consequence, the unit tests
were conveniently executed each and every time that the main target was
run.

in Xcode 5 the shell script phase had to be removed (see previous
commit). as a consequence unit tests can no longer be executed when the
main target is run. the next best thing therefore is to execute them
when the „Test“ action is selected for the main target. although less
convenient than the original solution, this at least makes it
unnecessary to switch the target to run unit tests.
update docs to refer to Xcode 5.0.2
Merge branch 'upgrade-to-xcode5' into develop (closes #183)