The per-AI "start_date" is a lot of custom code, and was rarely
used in the way it was meant.
While at it, also ported this part over to the new timer system.
One question that keeps popping up: "when do we release 2.0?".
NewGRF will force that at least 1.16 will be 2.0, but to not wait
for this, let's drop the "1." and be for ever done with that
conversation.
We are following in the footstep of giants here.
This means that for rail tunnel/bridges, the rail is first sold,
and the tunnel/bridge is destroyed after. This means destroying
tunnels/ bridges now often makes you money, instead of costing.
Similar, with road/tram tracks. Destroying a road+tram
tunnel/bridge now costs the same amount of money as first
removing the tram tracks and than destroying the road
tunnel/bridge. Especially as tram tracks generate money when
removing, this is a noticeable difference.
This is for consistency; most other objects add a # to indicate
it is the Nth of that object, except for Trains / RVs / Ships /
Aircrafts.
This becomes painfully apparent with unnamed vehicles in groups,
which do get a "#".
The tst_stationlist savegame had to be changed to start the correct
AI. In the old setup, all regression AIs had the same name, which
made it impossible to run both regressions in parallel. With the new
setup this is possible.
Although all files are available to run the regression, it won't
really work till CMake is introduced (which will happen in a few
commits from here)
