Started to implement the algorithm.  Refs #7788.
Checkpointing work.  Refs #7788.
Added type IBackgroundFunction_sptr. Refs #7788.
Checkpointing work.  Refs #7788.
Checkpointing work.  Refs #7788.
Checkpointing work.  Refs #7788.
Checkpointing work.  Refs #7788.
Checkpointing work.  Refs #7788.

Started to implement a Fit on multi-domain function (background)
Checkpointing work.  Refs #7788.
Corrected some coding errors.  Refs #7788.
Checkpointing work.  Refs #7788.
Fixed bugs during running unit test (unfinished).  Refs #7788.
Fixed bugs in fit peak.  Refs #7788.
Fixed some compiling errors. Refs #7788.
Progress on finish output data.  Refs #7788.
Removed some unused code.  Refs #7788.
Modified some properties.  Refs #7788.
Use multidomain in FitBackground.  Refs #7788.
Tried to fit background with multidomain.  Refs #7788.
Fixed some error.  Refs #7788.