if LBM files missing

Some folks (me!) deleted some of their LBM files decades ago. Game should not raise an exception if they are missing.
Handle ctrl-key
support strafing sideways movement

properly resubmitted, I hope.
Tank, turn turret with ctrl-click

Implements "strafe" move for tanks, in which ctrl-click turns the turret. The tank subsequently moves with the turret strafed.
Merge branch 'game_h_cpp_handle_ctrl_key'
minor string fixes

- added STR_ZOMBIE to English.lng, EnglishUk.lng, Russian.lng, German.lng
- fixed a few alien names in Russian.lng based on ufopedia.org usage
fix sign comparison warning
github doesn't think tabs are 4 spaces :(
don't stealth-change TU reserve from Auto to Snap

Fixes this problem: With time units reserved to autoshot, if a soldier with a
non-auto weapon ran up against the snap shot TU reserve limit, _tuReserved
would be permanently set to BA_SNAPSHOT. As a result, all subsequent soldiers
with auto weapons would actually erroneously reserve TU for snap shots.
Merge pull request #258 from hmaon/clean

added STR_ZOMBIE to several .lng files, fixed several Russian strings, fixed my code formatting, a compiler warning, and a TU reserve bug
add shift-to-run
Merge branch 'running'
- removed unused NodeLink class, a nodelink is now just an ID(number) of the linked patrol node
proper handling for fatally wounded soldiers.
- Fixed OpenXcom not accepting Unicode paths properly.
- Fixed occasional crash in LBM loading.