MainForm.cs: applied recommended practices for using strings
Speech.cs: small code reformatting
UpdateChecker.cs: applied recommended practices for using strings
PlaylistControl.cs: applied recommended practices for using strings
InfoForm.cs: applied recommended practices for using strings
InfoForm.cs: put gradientBrush into 'using' statement for IDisposable
SnapshotForm.cs: minor code formatting
UrlForm.cs: put gradientBrush into 'using' statement for IDisposable