Codechange: introduce a framework for all our timers

IntervalTimer and TimeoutTimer use RAII, and can be used to replace
all the time-based timeouts, lag-detection, "execute every N" we
have.
As it uses RAII, you can safely use it as static variable, class
member, temporary variable, etc. As soon as it goes out-of-scope,
it will be safely removed.
This allows for much easier to read code when it comes to intervals.

Fix: Whole status bar instead of money widget refreshed on money change (#8692)

This could result in the rest of the status bar being
redrawn unnecessarily frequently

Fix 2fd871e2af5: load correct ending-year for old (pre 0.7) savegames

Despite what it looked like, you could never really change the
ending-year (it was always reset to 2050 on start-up). See commit
683b65ee1 for details. As a side-effect, the variable that was
suppose to store the ending-year was just zero, never containing
a real ending-year.

Fix #8050: never show the highscore when disabled, not even if you start in year zero

Using zero as "never" value can have its drawbacks ;)

Feature: NewGRF callback profiling (#7868)

Adds a console command newgrf_profile to collect some profiling data about NewGRF action 2 callbacks and produce a CSV file.

Feature: Configurable game ending year

Functionally reverts 683b65ee1

Remove: ENABLE_NETWORK switch

This switch has been a pain for years. Often disabling broke
compilation, as no developer compiles OpenTTD without, neither do
any of our official binaries.

Additionaly, it has grown so hugely in our codebase, that it
clearly shows that the current solution was a poor one. 350+
instances of "#ifdef ENABLE_NETWORK" were in the code, of which
only ~30 in the networking code itself. The rest were all around
the code to do the right thing, from GUI to NewGRF.

A more proper solution would be to stub all the functions, and
make sure the rest of the code can simply assume network is
available. This was also partially done, and most variables were
correct if networking was disabled. Despite that, often the #ifdefs
were still used.

With the recent removal of DOS, there is also no platform anymore
which we support where networking isn't working out-of-the-box.

All in all, it is time to remove the ENABLE_NETWORK switch. No
replacement is planned, but if you feel we really need this option,
we welcome any Pull Request which implements this in a way that
doesn't crawl through the code like this diff shows we used to.

(svn r16909) -Fix [FS#2996]: NewGRF stations would be triggering assertions all over the place when using the more advanced station types.
-Change: make (rail) waypoints sub classes of 'base stations', make buoys waypoints and unify code between them where possible.

(svn r15077) -Codechange: enumify DAYS_IN_YEAR and DAYS_IN_LEAP_YEAR
-Change: when computing daily running cost, divide by 365 (instead of 364). Since r12134, the rounding errors don't need this correction anymore

(svn r14611) -Fix (r13437)[FS#2421]: Store the age of a house in the map array instead of the construction year.
Note: Savegames from r13437 to now are broken and have a age of 255 years for a lot houses.

(svn r14332) -Fix[FS#1885]: Balance the monthly random industry changes, by introducing a daily random industry change.
This will allow to perform more changes per month on big maps and less on smaller maps, while not overtaxing the IndustryMonthlyLoop process.
Thanks to frosch, for nice code ideas and rewrites

(svn r13251) -Codechange: rename _patches to _settings as that is more logic.
-Codechange: move all Settings into substructs of _settings in a way that they are logically grouped.

(svn r8862) -Cleanup: doxygen changes, again. Mostly @files missing tags and a few comments style.
Some documentation addition, when i can easily supply them

(svn r8621) -Codechange: assigned new numbers to the VEH_(type) enum so that VEH_Train is 0, VEH_Road is 1 and so on
This means that "v->type" can be used as array indexes instead of VehTypeToIndex() (or "v->type - VEH_Train/0x10 as the code still used in some places)
Surprisingly this can be done without changing the savegame format