and use in CheckWorkspacesMatch

Refs #11179

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

nof if I am familiar with this style or finding it clearer then usual file scope function.

Refs #9252

of Relerr with more careful treatment of values near 0 is preferable implementation.

Evaluating problem I am having comparing two similar inelastic workspaces I've modified comparison algorithm to work with relative and absolute error. This is actually what you want comparing two workspaces and some kind of this approach was already in place for values close to 0

Somebody did a good job making this algorithm look nice but useless, so I spent long time looking in amazement why workspaces which look identical do not match.
A coordinate (and sometimes signal and error! can be negative!) This fixes this problem.

by removing references to POCO methods which do not exist on Unix

by prohibiting parallel execution for CheckWorkspacesMatch in one selects "debug" and "trace" log levels

Mainly removed Poco includes and used forward declarations instead.
Unsuprisingly this has affected some algorithms.
Refs #8784

This algorithm property is only applicable to event workspaces (as the
property documentation states) but was being used for MD & Peaks
workspaces. However, the outcome if you pass in one of these workspace
types along with something else is a crash if the CheckType property is
false.

Therefore, always enforce a match for these types.

Also a hidey change over using std::fdim in favor of std::abs.