Rework linux launching scripts to reflect conda

[peterfpeterson]

This really is a cleanup of the scripts. It drops support for qt4, removes mention of mantidplot, and allows for taking advantage of conda.

In conda mode: let conda take care of the PYTHONPATH, don't do it in the scripts. This also re-uses CONDA_PREFIX which points at the location of the active environment. This does verify that the conda package is being used from an active conda environment.

In system mode: do what we've always done.

To test:

Run cmake . and compare the build version, install version, and previous install version of mantidworkbench and mantidpython.

There is no associated issue.

This does not require release notes because it should not affect users in any noticeable way.

---

Reviewer

Please comment on the following (full description):

Code Review

• Is the code of an acceptable quality?
• Does the code conform to the coding standards?
• Are the unit tests small and test the class in isolation?
• If there is GUI work does it follow the GUI standards?
• If there are changes in the release notes then do they describe the changes appropriately?
• Are the release notes saved in a separate file, using Issue or PR number for file name and in the correct location?

Functional Tests

• Do changes function as described? Add comments below that describe the tests performed?
• Do the changes handle unexpected situations, e.g. bad input?
• Has the relevant (user and developer) documentation been added/updated?

Does everything look good? Mark the review as Approve. A member of @mantidproject/gatekeepers will take care of it.

[peterfpeterson]

Real questions: Should the script be split into development is hooked onto CONDA_ENV and production connected to CONDA_BUILD? The code needs more work, but I think that is the distinction we need (assuming I understand the variables correctly).

[peterfpeterson]

Documenting conversation with @martyngigg. The new logic (for CONDA_BUILD=on) is

Get install location (current INSTALL_DIR)

• if it matches CONDA_PREFIX then launch mantid as usual
• else if conda exists conda run -n <conda environment> mantidworkbench $@[*]
• else error out

[peterfpeterson]

Variables that are useful for this:

• CONDA_DEFAULT_ENV points at the name of the conda environment that is active (e.g. mantid-dev)
• CONDA_PREFIX contains the full path of the current conda environment (e.g. /opt/anaconda/envs/mantid-dev)

Related branch

[martyngigg]

The RHEL7 build is no longer relevant so it can be ignored when considering whether to gatekeeper this.