[Lazarus] Type_Class_Explorer application

[Howard Page-Clark]

I'm contributing an application which you can find in the Third Party 
Announcements section of the online Lazarus forum (at 186k it's too big 
to travel as an attachment on this email list). It may be suitable for 
inclusion with existing Lazarus examples, now that the release of 
Version 1.0 gets nearer.

This class explorer displays information on all LCL Palette components, 
including the unit where it is declared and a visual hierarchy of 
ancestor classes, together with information on a variety of non-Palette 
LCL and FCL classes, and information on a range of simple types.

Additionally, almost every palette component that has visual GUI 
functionality is provided with a mini-applet demonstrating some simple 
feature of one or two properties, and a display which logs the commonest 
events (where possible) to give beginners a bit of simple working code 
to use. For the Chart components I've adapted code from Alexander's 
excellent examples (cut down to a bare minimum). Database examples are 
mostly based on TDbf, because although deprecated, it works 
out-of-the-box without requiring external database installation to 
obtain a working example.

I struggled with reliably working code for some RTTI components (see the 
TTIImage and TTIFLoatSpinEdit). Flickering may arise from poor coding on 
my part, or perhaps it is the OnIdle trigger setting properties repeatedly?

I'm not sure exactly which components will be installed by default into 
the Palette for Version 1.0, so the selection is based on RC1, and since 
component selection is unfortunately hard-coded (I'm not sufficiently 
experienced to work out how to do this dynamically), further adjustments 
may be needed to make the program work with a comprehensive Version 1.0 
component set.

Howard