Add a special mode where a Configuration does not deliver to the solver,
and use it in Configuration_mediawiki, preventing the files from
officecfg being overwritten by files from swext.
Should fix the annoying sc_test_filters failure and the smoketest
as well if the mediawiki extension is enabled.

First step before implementing Fade In/Out

 modify sax::Converter::convertMeasure to use sal_Int64 instead of BigInt:
  should be sufficient, since the largest number is SAL_INT32_MAX * 10^7.
 remove duplicate methods from SvXMLUnitConverter:
  convertMeasurePx, convertMeasure (static variants)
 remove entirely duplicative class SvXMLExportHelper:
  GetConversionFactor, GetUnitFromString, AddLength
 change SvXMLUnitConverter interface from MapUnit to css::util::MeasureUnit.
 change SvXMLExport constructor params from MapUnit to css::util::MeasureUnit.
 rename some methods to turn compiler into merge conflict detector :)

 remove duplicate methods from SvXMLUnitConverter:
  convertTime (all variants), convertDateTime (DateTime variants),
  convertTimeDuration.
 move convertAny from SvXMLUnitConverter to sax::converter.

 move convertNumber64 from SvXMLUnitConverter to sax::converter.
 remove duplicate methods from SvXMLUnitConverter:
  convertBool, convertPercent, convertColor, convertNumber, convertDouble,
  indexOfComma, encodeBase64, decodeBase64, decodeBase64SomeChars,
  clearUndefinedChars

No need to muck about with iterators, adding a loop, and 2 function
calls to test for empty: it's a std::vector under the hood, so use
.empty(), and inline it.