Split out LaTeXML::Post::MathML::Presentation and *::Content subclasses to separate files; absorbed PresentationLinebreak into Presentation class, but moved the utility class LaTeXML::Util::MathMLLinebreaker under LaTeXML::Post::MathML::Linebreaker;  Exported DefMathML and a set of needed utilities as an exploration on extensibility. NOTE: This is currently not Daemon-safe; extensions are not restricted to the current document or session
explicitly import LaTeXML::Post::MathML::Presentation
Make analogous exports for LaTeXML::Post::OpenMath so that experimental (but currently not Daemon-safe) extensions can be made; NOTE that the sub Expr() is now renamed om_expr() to be more consistent and safe
use withState method, rather than binding STATE
Explicitly require LaTeXML::Post::MathML::(Presentation|Content)
Explicitly require LaTeXML::Post::MathML::(Presentation|Content); remove redundant linebreak code
Explicitly require LaTeXML::Post::MathML::(Presentation|Content); remove redundant linebreak code
moved MathML subclasses