Various fixes to Load

Improved some long lines.

Fixed an issue where all the separator options weren't being shown.

CustomSeparator now has the same property settings as it's SaveAscii2 counterpart.

The comment and separator validation has been improved to disallow - + and e as they're part of the scientific notation. The separator = comment check is now bundled into the comment's regex check.

Refs #7732
Lots of imporvemetns ot SaveAscii2Test

Two repeated blocks of code are now factored into their own methods: Writing the sample WS, and initialising SaveAscii2.

Made the filename and WS name variables global.

Added many more tests to check fail cases.

Refs #7732
Imporved LoadAscii2 Test

Written failure cases

Refactored the data check method.

Added another paramerter to runTest.

Cleaned a few lines up.

Refs #7732