Fix error output streams

This MR fixes ErrorUtil so that when using Nektar++ externally, programs can redirect output from error messages. Presently this is broken as the error stream is a header-only variable, meaning that each library likely has its own variable for the error stream. It also makes a few additional changes to Tester:

• All Nektar++ library code has been removed (mostly ASSERTs but also the factory) which was preventing this from working with the changes, and also decouples the tests from the code entirely so that Tester is a standalone executable.
• A few compiler warnings fixed.
• Verbose mode now actually prints out some stuff during testing.

The remaining changes relate to removing boost::lexical_cast headers from ErrorUtil.

added 215 commits

• b9a2c5eb...ac53048b - 213 commits from branch nektar:master
• 1123c73a - Merge remote-tracking branch 'upstream/master' into fix/error-output
• 854e4884 - Add test for error streams, add verbose output to Tester and fix a few compiler warnings

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changed milestone to %v5.0.0

removed Proposed patch label

changed the description

added 271 commits

• 854e4884...0d233b67 - 270 commits from branch nektar:master
• ea27d2ea - Merge remote-tracking branch 'upstream/master' into fix/error-output

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@ccantwel @ssherw I have finished this branch off -- it's left as a WIP so that we can run through buildbot once that is back up. Can either/both of you check this one reasonably carefully in case I messed something up with Tester?

Since the changes are reasonably large I have now switched this over to %v5.0.0 from %v4.4.2 as well.

Hi Dave, I have had a look over the changes. Nothing obvious jumps out but I guess we need to run it through buildbot and we can see if any tester output are failing on different architectures.

Regarding the lexical_cast was it just that too many random headers were being declared or was there another reason for this tidy up. Presumably we might still need to use it to make strings to feed into the error message?

Yep absolutely, will run this through buildbot once I've sorted out the demo branch. Regarding lexical_cast, was just trying to remove as many headers as possible from this since it gets included everywhere.

added 34 commits

• ea27d2ea...ea5bc8b6 - 32 commits from branch nektar:master
• 71c2518b - Merge branch 'master' into fix/error-output
• b222d4ce - Update CHANGELOG

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unmarked as a Work In Progress

added 1 commit

• 2b3b5e04 - Fix missing boost/optional.hpp include required now in Geometry.h

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added 1 commit

• f862acbc - Fix many many errors in ErrorUtil that didn't get picked up because not testing in debug mode!

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added 1 commit

• fac99ae9 - Add missing include for VS

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added 1 commit

• 9567b2aa - Add missing LIB_UTILITIES_EXPORT for VS

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assigned to @ccantwel

Okay this now passes buildbot, I'm going to assign to @ccantwel when he gets a chance to look over since I don't really want to break everything