DSL: add `tags` stanza

only limited/defined keys are permitted
 - :vendor
 - :font_pitch
 - :font_serif
 - :font_weight
 - :font_slant

forward-compatibility: no associated functionality is
provided.  Intentionally left undocumented.

References: #4688
Add EverWeb (latest)
Add Sandvox (latest)
Docs: admit unstable releases in main repo
Add NoobProof 1.5
Add PFLists 1.0.1
Add iSteg 1.62
Merge pull request #5193 from ndr-qef/versions-doc

Docs: admit unstable releases in main repo
Merge pull request #5187 from alebcay/isteg

Add iSteg 1.62
Add Rust, nightly release
Merge pull request #5195 from ndr-qef/rust-lang

Add Rust nightly
Merge pull request #5191 from alebcay/sandvox

Add Sandvox (latest)
Merge pull request #5190 from alebcay/everweb

Add EverWeb (latest)
Merge pull request #5189 from alebcay/noobproof

Add NoobProof 1.5
Merge pull request #5188 from alebcay/pflists

Add PFLists 1.0.1
Add 爱奇艺视频.app v2.6.0
upgrade boot2docker to v1.0.1

https://github.com/boot2docker/osx-installer/releases/tag/v1.0.1
Merge pull request #5200 from honnix/master

upgrade boot2docker to v1.0.1
Adds Belgium eID (eid-mw) v4.0.6
Merge pull request #5199 from MrGba2z/qiyimedia

Add 爱奇艺视频.app v2.6.0