web.xml: set dev mode when in development
#1022 "Logged exceptions do not show extension parameters"

- update Errorified, see https://github.com/orbeon/errorified/commit/06773c183e3b799fc03a3d2fdbaf9e17143d3e0a
- move ValidationException and ExtendedLocationData to Scala
- use OrbeonLocationException object (progress on #910)
- don't bother ever putting Java location information
- Variable uses ElementAnalysis location data
- elementToDebugString doesn't bother with element content
- error.xsl doesn't parse XML element