Adding possible test suite system.

 Once again, we'll deal with linked lists, but this time with function
pointers in addition to all of the other stuff. It'll be somewhat
difficult to manage those, but they're just another struct member to
be dealt with, and that kind of system is not hard whatsoever to
manage (cite argument system)

Signed-off-by: Kristofer Rye <kristofer.rye@gmail.com>
Add prototypes for two more somewhat-necessary functions.
coding style: Change the comment style in argument.c

 Instead of having two practically-useless lines, one with "/*" at
the start of the block comment, and one with "*/" at the end of the
block comment, just have one at the end, and immediately start the
block comment at the opening line.

 This makes it more readable and less inefficient, especially for
one-line comments (which will get changed in the next commit).
coding style: Change one-line comment style in argument.c

 For one-line comments, still use block comment syntax, but don't
include the extra line at the bottom to close the comment; do the
entire comment on one line.
coding style: Change comment styles used in database.{c,h}

 Follows similar style to 665df80 and fe4ad27, but also includes
the use of one-liners at the end of the line (which also get the
block-comment-style comment syntax)
coding style: Fix comment style in the rest of the project files.