Version 0.7.2 (2007.02.28):
	* added buttons Sgn and Mod
	* the button 'err' is active when there's actually an error now
	* added buttons: ASin, ACos, ATan, ACTan
	* fixed: the program didn't save the current language into the configuration file
	* fixed: the second thread didn't read the main window correctly and it caused
	  small problems when an user was typing into the first edit control

Version 0.7.1 (2007.02.08):
	* added a button 'err' (error) on the first tab
	* the input edit can have 2048 characters now
	* added remembering the vertical size into the config file
	* fixed a problem with the 'tab' key
	* added a message 'Calculating...' when an user clicks on the 'err' button
	  during calculating something