Revert "Do not create an ‘LNVL’ table in the global namespace"

This reverts commit f772a3bfc71bfa622eb5770ebc8481f9654608a4.

We run into LÖVE blue-screens when loading modules via the
LNVL.Initialize() function.  This is because those modules do not see
the LNVL table.  The purpose of the original change was to avoid
naming conflicts when inserting LNVL into games.  However, I have
changed my mind about this and no longer believe the risk of conflict
is that significant.  So for the time being I would prefer the quick
fix of reverting the above commit.
Character: Add first and last name properties

This is useful because a lot of characters have full names and we want
to be able to sometimes display the full name or just the first name
in our scripts.
Character: Default to using the first name

This will help reduce redundancy where we want the name we display in
scripts to (usually) be the first name, so that we do not need to
define it twice when creating the character.
Character: Document the setName() method in the ‘Howto’

There is no implementation for the method, so this documentation also
serves as our technical design guide for how we want it to work.
Character: Rename the ‘name’ property to ‘dialogName’

Now that we have first and last names for characters the ‘name’
property is too ambiguous with regard to readability.  This patch
renames it to ‘dialogName’ because it is the property the we will
display in dialog windows by default.
Scene: Fix crashing caused by accessing character names

The code for tracking active characters uses the recently-removed
‘name’ property instead of the correct ‘dialogName’ replacement.
Character: Rename setName() method to displayName()

A method like setName() makes it sound as if we are changing the
character’s name, which is not its intent.  The method changes what
name LNVL displays.  Hence the new name.

Note that this patch still does not provide an implementation, only
documentation for how the method will behave.
Character: Implement the displayName() method

This patch also implements and documents the new opcode
‘set-character-name’ and the related ‘set-name’ instruction.
Character: Add a example test script for displayName()
Use ‘Markdown Styles’ for pretty HTML documentation
Merge branch 'expand-character-names'

* expand-character-names:
  Character: Add a example test script for displayName()
  Character: Implement the displayName() method
  Character: Rename setName() method to displayName()
  Scene: Fix crashing caused by accessing character names
  Character: Rename the ‘name’ property to ‘dialogName’
  Character: Document the setName() method in the ‘Howto’
  Character: Default to using the first name
  Character: Add first and last name properties