Clarified some errors and comments

Errors now include the line number in the file if it's avialable to them.

Some comments have been deleted or improved

Refs #7732
Refactored Save Algorithm

SaveAscii now validates the comment indicator and user defined separator.

The code has been refactored to split off the spectra writing code into a mthod with two overloads: one taking an int and one taking an iterator.

Some varables have become private member variables to help with the new methods

Refs #7732
Load Algorithm now compatible with custom separators

The Save Algorithm had always been able to define a custom spearator, but ht eLoad algorithm wouldn't recognise them.

Custom separator code now added to both algorithm and custom dialog.

Refs #7732