New unscripted testing page in developer docs

Fix missed GCC->GNU macro

Update CONTRIBUTING.md

Squashed commit of the following:

commit 7430d88e
Author: T Jubb <t.w.jubb@gmail.com>
Date:   Fri Aug 3 14:04:45 2018 +0100

    Refs #0 Revert PR template.

commit bfca2a5a
Merge: b7a9a09b ccc7a67d
Author: T Jubb <t.w.jubb@gmail.com>
Date:   Fri Aug 3 13:59:20 2018 +0100

    Refs #0 merge remote branch.

commit b7a9a09b
Merge: 3abde33d 16e27bdb
Author: T Jubb <t.w.jubb@gmail.com>
Date:   Fri Aug 3 13:55:47 2018 +0100

    Refs #0 merge master.

commit 3abde33d
Author: T Jubb <t.w.jubb@gmail.com>
Date:   Fri Aug 3 13:52:26 2018 +0100

    Refs #0 make changes as per comments.

commit a27f8a1a
Merge: 54684e10 b5ad845b
Author: T Jubb <t.w.jubb@gmail.com>
Date:   Fri Aug 3 13:51:18 2018 +0100

    Refs #0 merge master.

commit ccc7a67d
Merge: 54684e10 b5ad845b
Author: TWJubb <33163693+TWJubb@users.noreply.github.com>
Date:   Fri Aug 3 13:05:49 2018 +0100

    Merge branch 'master' into PyCharmDevDocs

commit 54684e10
Author: T Jubb <t.w.jubb@gmail.com>
Date:   Fri Aug 3 12:57:21 2018 +0100

    Refs #0 : Add PyCharm dev doc page.

Update third party and Fix sip build invocation

 Muon results table includes log values with value of 0

Fix clang warnings

Improve error handling for TableWorkspace

Minimal change to prevent a crash

Correct default doc string for empty property managers to dict()

SNAPReduce progress bar

Removed the LoadAscii Custom Dialog, it was out of date with the alg

Update MSlice to fix MakeProjection bug

Elemental Analysis: Peak Data Loading

Instrument definition file for DNS PSD detector

Fix detector rotations in TOFTOF IDF

Move time-weighted statistics to object

re #22807

RHEL7 devtoolset-7

re #22965
This dialog is not used enough to justify much more time being spent on neatening things up

ConfigService loading

Fix RunNumber bug in PeaksWorkspaces

Check existence of Poco debug libraries before using them

Separate dialogs and widgets into different mantidqt subpackages

The [cmake documentation of `CXX_STANDARD_REQUIRED`](https://cmake.org/cmake/help/v3.5/prop_tgt/CXX_STANDARD_REQUIRED.html)
demonstrate that this was previously incorrectly set. This forces the
compiler flag to be specified. In the case of gcc 4.8 it sets
`-std=c++1y`. Newer gcc (since version 5) will sets `-std=c++14`.

The TSC decided to move to devtoolset-7 on rhel7 to allow for C++14
standard code in mantid.

The Windows dependencies need downloading before Eigen is configured