Update to clang-format-5 and reformat the codebase 

Reflects comment in #5496.

Is there a reason why this class has all its implementation in the header?

Refs #3157 Sort our System.h. It was becoming a dumping ground. It should only be touched when absolutely necessary as it affects every file in Mantid. Also combined this with Refs #2345 to sort out DLLExport/DLLImport usage. It's done for Kernel, Geometry and API but stuff in the plugins could do with updating as well.

Add more flexible simple API command for Load. Re #2330. Clean up for memory leak in LoadSNSNexus. Re #2394

Blocking InstrumentWindow from accessing the instrument while an algorithm is running to prevent MantidPlot crashes. re #2133

Rename Framework code directory to just that. Also delete Main and VS & Eclipse project file. Re #1881.

Copyright updated to read
Copyright © 2007-10 ISIS Rutherford Appleton Laboratory & NScD Oak Ridge National Laboratory

Combined LoadDAE and UpdateDAE into one algorithm. Moved LoadDAE dialog to MantidQt. re #523, re #491

Clear some doxygen warnings

Update AlgorithmManager to only keep a limited number of algorithms alive (default 100, config property name: algorithms.retained). This check-in will break qtiplot, which will be remedied shortly... Re #500.

AlgorithmProxy class is added. References to Algorithm are replaced to IAlgorithm in many cases. re #464

re #379. Added class Progress which makes progress reporting even easier (I hope). Also AlgorithmObserver class is designed to make tests of algorithm notifications easier.