Show error in fitting tab

[Anders-Markvardsen]

Request from Steve Cottrell.

After a fit display the error in brackets

Type LinearBackground

A0 9.213 (0.040)

A1 7.123 (0.080)

Steve e.g. look at the errors when e.g. fit several exponential, where large errors can indicate strong correlation. He would
prefer to have this in the fitting tab rather than (remembering
to) they are in table parameter workspace, and he things in particular
inexperience users of Mantid would benifit from this also.

There should be an option in preferences to turn in on or off.
I am not sure what the best default value for this should be.

Regardless of this choice when this feature has been implemented
the Fitting tab in the muon interface will have this feature set
to on.

[Anders-Markvardsen]

This issue was originally trac ticket 6616