Tidy: header files, use forward declarations for Mudlet classes

Changed so that where possible, class declarations are used instead of
#include(s) for pointer references to other Mudlet classes in header files
so that changing the referred to class header does not require
recompilation of this class.

All #includes move to top of file (with a comment left as a marker) and
sorted into order, deleting ones found unnecessary for compilation.
*** THIS SHOULD BE TESTED ON MULTIPLE PLATFORMS/SETUPS ***
Order used is: non-Qt system, Qt system, Mudlet class templates
('T'*.h files), other Mudlet header files.

Header guards moved to first lines of files (before boilerplate
Copyright/Licence) and guard #define(s) made more uniform.
Odd spacing for end of boilerplate line '*' characters on lines
with E-mail contact address fixed on header files.
*** Still to do on .cpp files ***.

Spacing of types and member-names changed to be more uniform across
project and attempts to layout member arguments in a more uniform manner.
Attempted also to reset indent to a 4 character alignment.

Signed-off-by: Stephen Lyons <slysven@virginmedia.com>