Improve BHoM Upgrader handling of types

[adecler]

Issues addressed by this PR

• Closes Versioning_Toolkit: Recursive triggering is not happening for Old mode of serialisation #59
• Closes Versioning_Toolkit: Upgrader should be calling upgrade methods recursively for sub types #60
• Closes Versioning_Toolkit: Method upgrader reports false "modified" #61

The key change in this PR is the fact that upgrading a type that doesn't have any versioning information is now returning null (like for object and method) instead of the input type. Otherwise, simply making sure that methods can update their internal types through the chain.

Test files

Any old file you have at hand. See more links from #66

Changelog

• Fix recursive triggering not happening for Old mode of serialisation
• Fix Method upgrader reporting false "modified" types
• Upgrader now calling upgrade methods recursively for sub types

[kThorsager]

Tested on a few scripts in Grasshopper pre 2.4 and some post which used Versioning and all worked well

LGTM

[IsakNaslundBh]

Testscripts running fine