Fixed some compiler warnings.

Returning a const pointer (not a pointer to const) is not really useful, since
returns of scalar types are by value.

The warning was produced by g++ 4.7.2, using -Wignored-qualifiers.
Fixed memory leak in Game::loadLanguage().

We are now properly destroying the sidebar surface.
Return constant references to rules' lists.

Since no-one is modifying these lists, return them as constant references.
This allows the calling code to avoid copying them.
Avoid creating deep copies of ID lists.

Take advantage of the const refernce return to avoid making copies of the
various ID lists from the rules.
Const-corrent Ruleset::getPools()

Besides making it const, changed it to return a const reference to the
underlying std::vector. Returning references (instead of pointers) to containers is
better C++ practice.
Make Ruleset access through const.

Only the Game has a non-const pointer to Ruleset now.
Every other class uses a const pointer, except when loading rules.
Fixed some compiler warnings.

Returning a const pointer (not a pointer to const) is not really useful, since
returns of scalar types are by value.

The warning was produced by g++ 4.7.2, using -Wignored-qualifiers.
Graph Screen Grid Rendering

a relatively simple method to render the grid to display our data.
this is the most efficient method i could come up with.
also: it looks correct to the pixel.
Let's enable those other buttons

let's provide functionality for those 5 buttons, even if they won't do
anything yet.
Add Horizontal Scale to graphs

this commit is a bit like me really... raw, brutal, horrifically ugly but
dammit, it gets the job done.
if you don't like it, then YOU spend 3 hours trying to get this crap to line up.
Add Vertical Scale to graphs

oh god, this is a mess.
this class is starting to suffer some serious bloat issues,
but for the life of me, i can't figure out a better optimized method that
results in the text actually being where i want it.

if you can think of a better method... don't hesitate to send a PR.
Fixed bad formula - graph complete!

that didn't look right at all.
this looks a LOT better.

oh also, the graphs screen now has a working graph (background) that scales
properly according to the scores it's measuring, accurately displays month
and year information, and STUFF!
Bugfix for crash on debriefing

checking that we have a valid pointer doesn't work as a boolean expression.
so instead i used a boolean expression.
who would have guessed? that fixed it.
Merge branch 'master' of https://github.com/SupSuper/OpenXcom.git into ActivityScreens
Refactor: save more funding info

we now store the last 12 month's worth of month-ending funding levels.
because your savedgame is evil and needs to be punished.
more refactoring + code cleanup

and a few more coding buzz words.
moved some of the things we'll be doing a lot out into their own functions.
those buttons actually do something now, they change the vertical scale
units of the graph.
still no LINES drawn on it yet, but i'll need 7.4 billion buttons for that.
7.4 billion buttons added.

one for each country and region, and a total for both.
this is SO not gonna be modder friendly.
they'll have to add buttons by haxxoring code.
better graph scaling

now we have nice round numbers on the graphs screens
using these methods to get the results i wanted makes me sick to the stomach
if someone can come up with a formula that does the same thing PLEASE send a PR,
because this feels like the worst optimized piece of shitty code i've submitted.
i could substitute the series of else-ifs to a case statement, but that's just
a different way of dealing with the problem, not a solution.
Code Optimizations

aka: how i learned to stop worrying and love the array,
commonly known as "vectors! vectors! hooray for vectors!"

- refactored 7.4 billion buttons into 2 vectors who's size is a function
of the number of countries/regions defined in the ruleset.
- reduced overall file size considerably, while simultaneously adding modability support.
Make buttons prettyful.

now that we have too many buttons, let's make them all do something.
for starters, let's make the graph selection buttons display the right set
of buttons, and let's create some variables/pointers to use further on down
the road (for example, an array of which buttons are currently on)

then, let's make the country/region buttons toggle their colours
on and off when you click on them.