Saving and position columns bug fixes and changes

[dannyparsons]

1. Fixed functionality so that when replacing an existing column, it stays in same position by default and also added parameter to the R methods to allow it to be moved when replaced (a control for this can be added to the positioning sub dialog in a separate PR)
2. Fixed bug in calculator where the before parameter, and therefore positioning a new column, was changed when reopening the dialog
3. Added strAdjacentColumn as a parameter to assign to methods as this is now part of the saving options

@africanmathsinitiative/developers This is ready for the review. 1. needs to be reviewed across dialogs that use the save control, please test carefully as this edits core parts of saving columns, and 2. only needs to be checked for the calculator dialog

[lloyddewit]

@Patowhiz You've done quite a bit of work in this area, please could you peer review? thanks

[rdstern]

Good

[Patowhiz]

This looks good. Tested it across multiple dialogs that use the ucrSave control. ucrSave control will need to be modified to enable positioning of existing columns and take advantage of the new parameter added. Issue #6002 will also need to be reopened to reimplement the functionality requested.

Just a few questions to @dannyparsons.

[Patowhiz]

@dannyparsons @lloyddewit, on a separate note, now that @dannyparsons has worked on the SetAssignTo() subroutine, I think in line 218 If bUseBaseFunction Then 'TODO SJL 07/04/20 Use ElseIf? of clsRSyntax.vb.
The todo could now be done by adding the ElseIf as recommended

[dannyparsons]

Thanks, done and addressed the comments.

[Patowhiz]

@lloyddewit this looks good to me.