new file: LoadSassenaParams.h
new file: LoadSassenaParams.cpp

This reverts commit a9c8a59a.

Allow filenames specified with the format <<short><operator>>...<short>
where:

<short> = <dir><inst><underscore><runs><ext>
<operator> = "+" or ","
<runs> = lists and/or ranges of (possibly added) runs e.g. "12,13+14,15:20".

See header file of MultipleFileProperty for more info on syntax.

This enables workspaces loaded through the algorithm to have a history that
can be used to reproduce the workspace properly.

MWRunFiles widget of LoadDialog now remembers the exact text a user typed -
in this way any user who types "INST0-50", clicks "Run" and reopens the
dialog is not met by a huge string containing a list of all 51 fully
resolved files, but rather their original input.

Changed the vector<vector<string>> templated versions of the toString and
toValue functions to accept customised delimiters.  This enables us to add
an option for the user to turn off multifile parsing if they are crazy
enough to want to load files with a plus or a comma in their path.

Changed the inner workings of Load for multi files.  No longer calling sub
algorithms with setChild or alwaysStoreInADS.  All workspaces are
essentially created outside the ADS and managed by the algorithm, right up
until the OutputWorkspaces are set.

Tests added where appropriate, but the majority of parsing cases are already
covered by MultiFileNameParser.

Also, raise exceptions where we were previously reporting to log and calling
sys.exit().

Rename HighOrderPolynomialBackground to simply Polynomial.

Unfortunately, this didn't work properly on Linux so we'll need to go back to the old way.

This reverts commit 5e0bdea6.

Also transforms from the old 'AllAxes' setting to the new per-axis
settings the first time a build containing this code is run.

Allows greater control. Just a bit left to do on loading/saving preferences and color fill plot behaviour.

Unfortunately, I made a dumb copy-paste error last time.