Fix misuse of FBOUNDP

[shamazmazum]

Hello.

This patch fixes misuse of FBOUNDP which is used to determine if a slot is existing and bound in the object, but only can be used to check if a symbol is bound to a function. The incorrect use makes codex unusable.

Also, there is a possibility that I missed something and there are more places in src/macro.lisp where unbound slots can be accessed. But I checked with my libraries which use codex for documentation and all works fine.

And also, It can be good idea to refactor your code and avoid use of SLOT-EXISTS-P and SLOT-BOUNDP completely using a generic function for collecting rows for the table and specific methods for each node class like so:

(defgeneric collect-rows (node)
    (:method-combination append))
(defmethod collect-rows append ((node class-node))
    (list (make-row ...)
           (make-row ...)))
(defmethod collect-rows append ((node struct-node))
    (list (make-row ...)
           (make-row ...)))
;; etc

[eudoxia0]

How strange. I thought I knew how it worked. Would you kindly split the PR up? There's other changes e.g. to the CSS. Also I don't want to change the build status flag.

[shamazmazum]

Sorry, I forgot to create a separate branch. Done in #32