The reason for separate classes for each type, instead of a more flat
structure is to enable easy discovery of the available arguments that
can be set. For L we'll have about 12 types with 30 arguments and
almost all of the arguments are type specific. In future releases
we'll introduce more arguments. With editors that have code completion
one can construct a span without having to consult the documentation.
For now it only contains Text and Cardinal types.
Change-Id: I94531e600133d9f4f59a4170cceef1ee7a360ca7
6c472fe969