Update to clang-format-5 and reformat the codebase 

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re #15289

also editied a couple of parameter dscriptions to fir better.
re #11822

Refs #9926

The converted text is stored in separate .rst files in the docs directory.
Refs #9562

Refs #8138

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>

re #6485

Touches nearly everything unfortunately but is necessary.

Also modified unit test to sometimes have spaces after commas.

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>

Refs #3984 Took the wiki description from every algorithm's wiki page and placed it in a comment in the CPP file (instead of the header file).

Continue obsession with const: ExperimentInfo(MatrixWorkspace)::getInstrument now returns a const instrument. Re #1944.

Eradicate IInstrument. Instrument's the one to talk to now (it was the only descendent class anyway). Re #2041.

Refs #2572: Added an initDocs() for all algorithms that sets the summary string to display in the dialog, as well as the wiki summary for possible later auto-wiki-fication of documentation.