Big Macro Improvements

much better macro implementation:

• the arguments of macros and the macro type can now be specified in JavaScript, making the parser more or less independent of new macros (see macros.ls for documentation)
• macros return an array of nodes or strings
• thus, the limitation of always treating groups as macro parameters is gone
• prevent macros from calling JavaScript Object methods

more features:

• use CSS variables for lengths
• implemented diacritics (text-mode accents)
• implemented counters, calc expressions, printing counters
• sections use now use LaTeX counters and not CSS counters anymore
• implemented \label and \ref
• implemented \verb

reimplemented lists:

• enumerate items can now be \label'd and \ref'd
• labels for all lists are now defined by counters and macros like in LaTeX
• max. list depths are adhered to

other new macros:

• \the, \value
• \message, \showthe
• \endinput

misc:

• refactor code (symbols and macros in their own files)
• bugfixes (url charset, float, quotes, empty lines after \item, ] in environments, dependencies)