Halved thumbnail size on concrete-viaduct

I changed the size of the thumbnail but am not sure of the correct
position. Pak compiling for some magical reason isn't working.
Revert "Halved thumbnail size on concrete-viaduct"

This reverts commit 2dab690c63841dafc353bd9326a7f901699458fd.
Revert "Revert "Halved thumbnail size on concrete-viaduct""

This reverts commit 1d553061ac7d7714af37f6dad85b12ed9695cfbf.
Revert "Revert "Revert "Halved thumbnail size on concrete-viaduct"""

This reverts commit 5135b8131d66ed14192866ae56e1639a0c67951a.
All concrete structures icons

I updated all the icons to specification. Some seem a bit unfocused, but
that's probably due to the fact that I worked with them at 800%
resolution
FIX: Various errors with steam locomotive tenders.
Class 7P tender speed

The locomotive updates with the removal of the streamlined version but
the tender is limited to 155, instead of 160 like the locomotive
End of choose signal underground limitation

Underground limitation removed, due to no other end_of_choose rail
signal being overground before 1970.
FIX: Underground 1938 stock could not be upgraded to BR Class 483
FIX: Tyneside EMU did not retire
FIX: Rear carriage of the SR 4-Cor did not transition to BR blue livery
SR Bulleid/Raworth CC - Electrification type

Electrification type is overhead (at least on pictures), but noted as
third rail. Change to overhead proposed.
Revert "SR Bulleid/Raworth CC - Electrification type"

This reverts commit 7f5446ab959fce639271177866798ee9c6d30770.
SR 4-6-2 axle load fix

Old weight displayed at 99t per axle, now 21t like the original vehicle
Added bio to traction types in late depots

An old depot is needed to use the post boy. They are vital for people
who take care of postal networks in smaller cities and should be
available throughout the game.
Roof Graphics Improved

http://forum.simutrans.com/index.php?topic=14207.0

Roof image fix
Merge branch 'half-heights' of https://github.com/Spenk009/simutrans-pak128.britain.git into half-heights
REVERT: End of choose signal underground limitation
FIX: Disable building of the noise barrier for now, as this does not currently seem to be supported in the makeobj code.
FIX: Errors in bridge icons
ADD: New industry graphics (including a new industry type, the supermarket) from Standard, with a few adjustments.
FIX: Miscellaneous bugs (from Standard)