(svn r10375) [0.5] -Prepare 0.5 branch for release of 0.5.3-RC1.

(svn r10374) [0.5] -Backport from trunk (r10333, r10336, r10337, r10345, 10346, 10368):
- Fix: Waypoints could be renamed when you are not the owner (r10368)
- Fix: The 'old' pathfinders (OPF and NPF) for road vehicles could not find a path when in a tunnel [FS#290] (r10345, r10346)
- Fix: Only add the autoreplace menu when autoreplace actually knows about the group [FS#880] (r10337)
- Fix: Signal state sometimes not properly set when the signal "pathfinder" reached the end of a line [FS#910] (r10336)
- Fix: News messages were shown over the endgame/highscore windows [FS#943] (r10333)

(svn r10373) [0.5] -Backport from trunk (r10306, r10311, r10317, r10339, r10344):
- Fix: Acceleration for trains on slopes is not calculated properly [FS#786] (r10317, r10344)
- Fix: Rail could be destroyed when building tunnels (r10306)

(svn r10372) [0.5] -Backport from trunk (r10288, r10290, r10293, r10294, r10295, r10347, r10348):
- Feature: Make the client list window (for network games) stickyable (r10293)
- Fix: Smooth economy did not close primary industries and it allowed increasing of production of industries that should not have rising productions (r10290, r10347, r10348)
- Fix: Flush the output of the dedicated server console (r10295)
- Fix: The "pause" key did not work in the scenario editor (r10294)
- Fix: Age non-front engines too (so when you move engines around in the depot they do not get age 0 when they are much older [FS#202] (r10288)

(svn r10307) [0.5] -Fix: Got 0.5 compiling on OS/2 again

(svn r10285) [0.5] -Backport from trunk (r10284):
- Fix: don't make everyone spectator if 1 joining client failed to create new company (r10284)

(svn r10282) [0.5] -Fix: compilation without networking support.
[0.5] -Fix: crashes with subsidy messages when using Korean as language.

(svn r10281) [0.5] -Backport from trunk (r10186, r10229, r10251):
- Fix: [Windows] Do not mess desktop when using ALT-TAB [FS#876] (r10251, r10186)
- Cleanup: removed duplicate include (r10229)

(svn r10280) [0.5] -Backport from trunk (r10109, r10219, r10222, r10230, r10246, r10258):
- Fix: Do not look in every direction for tunnels when building one, one direction is enough (r10258)
- Fix: Take the age of the front vehicle for station rating (r10246)
- Fix: Terraforming wipes out canals. Now you always have to remove the canal before terraforming, instead of "just" removing the canal [FS#594] (r10240)
- Fix: Only 2 trains could crash at one time as collision checking stopped on the first hit. This could technically cause desyncs in network games as the collision hash order is not guaranteed [FS#892] (r10222)
- Fix: Land under foundations was terraform when it shouldn't be terraformed [FS#882, FS#890] (r10219)
- Fix: Some NewGRFs use the same (unused in the "current" climate) sprite IDs. Normally this gives some artefacts, but when one NewGRF expects it to be a sprite and another NewGRF overwrites it with a non-sprite nasty things happen (drawing a non-sprite crashes OTTD) [FS#838] (r10109)

(svn r10279) [0.5] -Backport from trunk (r10139, r10153, r10154, r10155, r10165, r10187):
- Fix: Do not make a 270 degree turn on the international airport when a 90 degree turn is enough (r10187)
- Fix: Crash when trying to get the aircraft movement state of an aircraft going to a just deleted airport [FS#874] (r10165)
- Fix: Airports did not flood when there are aircraft on the airport [FS#601] (r10155)
- Fix: Some vehicles were not drawn when having a high resolution and a high zoom-out level [FS#870] (r10154)
- Fix: Vehicles disappear when crossing certain tiles [FS#869] (r10153)
- Fix: OpenTTD assumes that the resolution is at least 1 by 1, so force the resolution to be always at least 1 by 1 (r10139)