IVSD portable mode

While this file sits next to ivsd.exe, IVSD keeps its preferences, swatch and
graphic style libraries, added fonts, crash-recovery files and logs in the IVSDData folder
beside it, and writes nothing to %APPDATA%. Copy the whole folder to move IVSD with its
settings. The first time IVSDData is created, any settings already in
%APPDATA%\IVSD (or an older VectorCraftData copy beside this one) are copied into it; the
originals are left where they were.

Keep this folder somewhere only you can write to: whoever can write here decides your settings,
including the plug-ins and fonts folders IVSD loads from, and the Data Recovery copies of
your unsaved documents are kept here too.

Delete this file to use the normal per-user settings folder (%APPDATA%\IVSD) instead.
If IVSDData can't be written (for example on a read-only drive), IVSD logs a
warning and uses %APPDATA%\IVSD instead.
