refs #9022 Should solve the problem

by prohibiting parallel execution for CheckWorkspacesMatch in one selects "debug" and "trace" log levels
refs #9022 Incorrect comparison fixed
refs #9022 Histogram data comparison also serialized when requested
refs #9022 Unit test for log levels
refs #9022 fixing unix build

by removing references to POCO methods which do not exist on Unix
refs #9022 Reverting CheckWorkspacesMatch to division under fabs

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.
refs #9022 No, this actually fixes negative values problem
refs #9022 Proper error estimation

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
refs #9022 after some thinking, I've decided that standard definition

of Relerr with more careful treatment of values near 0 is preferable implementation.
refs #9022 A simple comment
refs #9022 Trivial changes to the function arguments
refs #9022 conflicts with master after long inactivity period

Merge branch 'master' into feature/9022_serialWorkspaceComparison

Conflicts:
	Code/Mantid/Framework/Algorithms/src/CheckWorkspacesMatch.cpp
refs #9022 Missing pre-commit

why it get missing in the first place?
Merge branch 'feature/9022_serialWorkspaceComparison' into develop