TradeWindow: fixed coding style

Mentioned here: https://github.com/zinnschlag/openmw/pull/554
Merge remote-tracking branch 'greye/cross-cell'
Fix for operations widget - hides when no operations are running.
Merge remote-tracking branch 'graffy76/recentfiles'
updated credits files
fixed various warnings about converting size_t to int
apply MSVC warning settings to shiny projects
Merge remote-tracking branch 'blunted2night/size_t-warnings_v2'
fix and unify object cell change update in mwrender