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.
Missing files from last commit
Merge branch 'game_h_cpp_handle_ctrl_key'
- Base defense quick battle removed from mission selection for now
avoid crash from mindprobing empty tile
Merge pull request #255 from hmaon/master

crash from mindprobing empty tile, fixed
fix for sound clicks in samples from .CAT files
- Proper damage type when units stand in smoke.
Merge branch 'master' of github.com:SupSuper/OpenXcom
Merge pull request #256 from hmaon/master

insufferable clicks and pops in samples from MS-DOS version .CAT files (fixed)
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'