Remove deprecated code

[balthisar]

Inspecting the newest generated API docs (http://www.html-tidy.org/tidylib_api/deprecated.html) there are some deprecated functions. 5.0.0 might be a good milestone for removing them.

[geoffmcl]

@balthisar feel the next release of tidy after such a long time should be as binary compatible to the last as possible...

Maybe a good idea for a 5.1, 5.2, ...

ps: The above link is now broken...

[balthisar]

Fixed link. Agreed.

[geoffmcl]

@balthisar has the time for this beast at hand?

[geoffmcl]

Maybe for release 5.2, or later... for now closing this...