Re-indented target "sf-os-compile" (following best guess as to the standard) to make it easier to read.

Re-assessed some of the raptor error messages to reflect the inconsequential nature of missing the MS dev tools when not trying to build the tools target.

Changed mergeXML.pl to use a better version of the XML printing algorithm, so it can generate well-formed content if the input includes some rogue &s or <>s.

If any files are in both the list of SDK headers, and the list of RnD headers, then they're only zipped in the binaries_epoc_additional zip, and not the binaries_epoc_sdk zip.