v2.2

• The QAPPLICATION_CLASS macro can now be defined in the file including the
  Single Application header or with a DEFINES+= statement in the project file.

v2.1

• A race condition can no longer occur when starting two processes nearly
  simultaneously.

Fix issue #3

v2.0

• SingleApplication is now being passed a reference to argc instead of a
  copy.

Fix issue #1

• Improved documentation.