P3.4: update Windows installer docs

We now overwrite puppet.conf settings based on the MSI properties,
and there's a memory effect you may need to watch out for too.
P3.4: Change Fedora service name back to puppet
P3.4: Note that Puppet can manage symlinks on Windows now
Win: Note that domain users can be local group members
Win: Extensive updates to package tips

Explaining the deal with versioning, etc.
P3.4: Update class containment docs with new contain function
Fix wrong info re: stages and class containment

I had this wrong the first time. See the code here to test the various permutations:

https://github.com/nfagerlund/evil-made-manifest/blob/master/contain_stages.pp
Mention contain function in the bgtm
P3.4: Create new experimental features section in PRM

- Split general future parser stuff and lambda stuff
- Still need to write the overview page
- Still need to strip out the lambda stuff that got removed for 3.4.
- Still need to paste in binder stuff and add msgpack stuff... maybe the binder
  stuff can just be a link to the ARM, since it's become a dead-end.
P3.4: Add $trusted hash to special variables section of language reference

This commit documents $trusted under the assumption that PP-773 and PP-765 are
already fixed.
P3.4: Add experimental features overview page
P3.4: Add experimental msgpack page
Add Windows instructions for msgpack support
P3.4: Update lambda docs with changed/removed functionality
Make experimental section of PRM sidebar more compact
Whoops, structured data facts exist on windows now
P3.4: Add docs stub for abandoned data binder work
Take 'more sections coming soon' out of sidebar
Windows: Don't call 'em "self-extracting exe"s

"Executable installer" is more accurate and useful.
Make Windows upgrading section match new 3.4 behavior

Missed one!