browsing docs in hilfe

hi,

pike documentation now at your fingertips!

please take a look at the new doc command in hilfe.
it is far from perfect, but i hope it is usable.

one flaw that needs fixing is the ability to look at docs from class
members without instantiating the class. currently an actual function
reference is needed.

if you find other issues, please let me know.

i am not sure how much overhead the added cache_source() will create.
but i hope it is acceptable. 

actual parsing of docs will only happen when the show_doc() function is
used, and then only one class at a time, which should be fast enough for
interactive use.

the big thing that is missing is of course the docs from the c code.

i am not yet sure how to handle those, but i think the best option would
be to create a compact version of plaintext docs or possibly encode the
AutoDoc objects into files, while pike is being compiled. these files
could then be distributed with pike as "runtime docs"

formatting of the output might also be improved. right now the docs are
displayed as is. for the most part this is readable enough, but so far i
have only looked at a few examples.

greetings, martin.