Tidy up code by removing the duplicate definitiosn related to _iterPerExp methods

Issue/feature addressed

There are unnecessary duplicate methods called BwdTrans_iterPerExp, IProductWRTBase_iterPerExp and GeneralMatrixOp_IterPerExp which are left over from an older version of the code when we supported GlobalCoeff and LocalCoeff space for expansion coefficients. Also the name IterPerExp was not very informative

Proposed solution

Remove the duplicate functions and only have BwdTrans, IPrductWRTBase and GeneralMatrixOp. Renameed FwdTrans_IterPerExp to FwdTransLocalElmt and to be consistent also rename FwdTrans_BndConstrained to FwdTransBndConstrained.

Implementation

Remove the duplciate code, including some overloaded functions in ContField that are now no longer required

Tests

Notes

These methods are run in all standard tests so existing test suite shoudl be sufficieint

Checklist

• Functions and classes, or changes to them, are documented.
• User guide/documentation is updated.
• Changelog is updated.
• Suitable tests added for new functionality.
• Contributed code is correctly formatted. (See the contributing guidelines).
• License added to any new files.
• No extraneous files have been added (e.g. compiler output or test data files).

Warning

On the 19.07 the code formatting (code style) was standardised using clang-format, over the whole Nektar++ code. This means changes in your branch will conflict with formatting changes on the master branch. To resolve these conflicts , see #295 (closed)