Lua: marshal Block values as userdata objects

Properties of Block values are marshalled lazily, which generally
improves performance considerably. Script users may also notice the
following differences:

  - Block element properties can no longer be accessed by numerical
    indexing of the `.c` field. The `.c` property now serves as an alias
    for `.content`, so some filter that used this undocumented method
    for property access may continue to work, while others will need to
    be updated and use proper property names.

  - The marshalled Block elements now have a `show` method, and a
    `__tostring` metamethod. Both return the Haskell string
    representation of the element.

  - Block values now have the Lua type `userdata` instead of `table`.

0 files changed, 0 insertions, 0 deletions