Compiler and documentation cleanup

[rhizoome]

• Enable -Werror
• Fix remaining compiler errors
• Fix documentation error

@stefanct this is minor cleanup.

[stefanct]

What's the problem with the empty braces?
And why is that dim there in the first place? :)

[rhizoome]

1. Half a year ago gcc on my system used to complained something like:

No body not allowed by ISO-C.

Now its ok, again, gcc seems not decided on the issue. I'll revert it. Since I already added the {}.

2. Without the dim:

$> gcc -I.. queue.c
queue.c: In function 'sglib_iq_is_full':
queue.c:18:1: error: macro "SGLIB_QUEUE_IS_FULL" requires 5 arguments, but only 4 given
SGLIB_DEFINE_QUEUE_FUNCTIONS(iq, int, a, i, j, MAX_PARAMS);

Its quite obvious the macro-body has dim and the called macro wants dim.

@stefanct I'm quite curious if Marian Vittek wil answer his email. 😄