common: Add ExpressionMatchTests unit tests
Add ExpressionMatchTests class to test the functionality of
ExpressionMatch, helping ensure it works across Qt 4 and Qt 5.
This is implemented as a series of Q_ASSERT()'s as Quassel does not
yet have an actual testing framework. Once a test framework is
settled on, this class can be migrated to unit tests.
To use ExpressionMatchTests:
1. Include it in "quassel.cpp"
2. Call ExpressionMatchTests::runTests() near end of Quassel::init()
// DEBUG: Run tests!
ExpressionMatchTests::runTests();