v3.0a

• Depricated secondary instances count.
• Added a sendMessage() method to send a message to the primary instance.
• Added a receivedMessage() signal, emitted when a message is received from a
  secondary instance.
• The SingleApplication constructor's third parameter is now a bool
  specifying if the current instance should be allowed to run as a secondary
  instance if there is already a primary instance.
• The SingleApplication constructor accept a fourth parameter specifying if
  the SingleApplication block should be User-wide or System-wide.
• SingleApplication no longer relies on applicationName and
  organizationName to be set. It instead concatenates all of the following
  data and computes a SHA256 hash which is used as the key of the
  QSharedMemory block and the QLocalServer. Since at least
  applicationFilePath is always present there is no need to explicitly set
  any of the following prior to initialising SingleApplication.
• QCoreApplication::applicationName
• QCoreApplication::applicationVersion
• QCoreApplication::applicationFilePath
• QCoreApplication::organizationName
• QCoreApplication::organizationDomain
• User name or home directory path if in User mode
• The primary instance is no longer notified when a secondary instance had
  been started by default. A Mode flag for this feature exists.
• Added instanceNumber() which represents a unique identifier for each
  secondary instance started. When called from the primary instance will
  return 0.