Update encoding for new NSFormatter subclasses

[gcasa]

This PR is to implement the encoding for all of the NS*Formatter classes that were previously added. The test for this is here... https://github.com/gcasa/EncodingTest. You will need to decode the compressed plist using this...

for i in `ls *.archive`\ndo\nplutil -convert xml1 $i\necho $i\ndone

I have implemented the keys as this indicates. I am currently testing this with the changes being made in Gorm to add inspectors for these changes... that branch is this... 91-add-a-palette-to-support-other-formatters.

[gcasa]

Changes for this are complete. Please review and let me know.

[rfm]

While all the changes look good, I think they would be better with testcases in Tests/base/... so that we know they actually perform OSX compatible coding.
The EncodingTest project looks like a start, but needs to have all the external dependencies removed and to be reworked to be part of the testsuite (ideally as a set of testcases which will run on both Apple and GNUstep).
I know we have a lot of testcases which work on one platform but not the other: let's strive to improve that.

[gcasa]

While all the changes look good, I think they would be better with testcases in Tests/base/... so that we know they actually perform OSX compatible coding. The EncodingTest project looks like a start, but needs to have all the external dependencies removed and to be reworked to be part of the testsuite (ideally as a set of testcases which will run on both Apple and GNUstep). I know we have a lot of testcases which work on one platform but not the other: let's strive to improve that.

Sounds good. I will do that today.

[gcasa]

I have all tests passing now. Also I used the *.archive files created by the unit test I had attached to add tests for all formatters and to make sure that the keys that are being create are the ones being used by GNUstep so that keys are macOS compatible.

[gcasa]

I believe this is now ready for review. Please let me know what you think @rfm