Fixed: PairedFloatControl had incorrect initial link icon.
Internal, AngleControl: rewritten AngleChanged event so it behaves like the rest of custom events.
Updated GZDB icon.
Fixed, Texture Browser Form: well, I broke "Tab" key functionality again (in previous commit)...
Maintenance: changed curly braces style to match DB2 one (hopefully not breaking anything in the process...).
Maintenance: changed private method names casing to match DB2 one.
Visual mode: "Lower/Raise Floor/Ceiling" actions now work on surfaces with sector slopes.
Cosmetic: numeric textboxes, which support relative values, now have differently colored text and a tooltip.
Internal: renamed Sector.CeilingSlopeOffset to Sector.CeilSlopeOffset, Sector.CeilingSlope to Sector.CeilSlope to match their names with similar sector properties.
Internal: UDMF sector slopes and offsets are no longer stored in sector.Fields. Use sector.FloorSlope, sector.FloorSlopeOffset, sector.CeilingSlope and sector.CeilingSlopeOffset.
BCC script compiler (https://github.com/wormt/bcc/) is now bundled with GZDB.
Main Form, "File" menu: only existing files are now added to the "recent files" list.
