Explore unknowns

[alandefreitas]

Based on the internal discussion held on October 21st, the project will concentrate on the following areas of uncertainty:

• Scripting extensions Explore Javascript Engines #881
• Plugins Add plugins/generators via DLL #58 define how the plugins are found #1044
• Cross-linking support for reading tagfiles #1072
• Reflection Explore reflection #1114
• Mrdocs-as-compiler Explore mrdocs as compiler mode #1073
• JSON-only mrdocs

This issue serves as a reference for the list and a platform for more lasting discussions about these topics.

[alandefreitas]

Update: The idea of a MrDocs version that only outputs JSON has been discussed internally this week. I'm adding this to the list of unknowns because it's independent from the idea of MrDocs as a compiler, even though Peter Dimov proposed both at the same time.

This unknown is similar to #678, but the pros and cons are inevitably different because some of the cons in #678 no longer apply, and we have other unknowns that could change the incentives here.

Also, there's some urgency to discussing this one because it completely changes the meaning of the unknown regarding extensions.