farewell to old-style mem infixes -- type inference in situations with mem_int and mem_string should provide enough information to resolve the type of (op =)

constant name access lattice is not in use any longer

uniform treatment of length = 1 for forced breaks, also makes ML/Pretty.length coincide with Scala/XML.content_length;

replaced slightly odd fbreak markup by plain "\n", which also coincides with regular linebreaks produced outside the ML pretty engine;

added separate;

basic formatting of pretty trees; line-up ML vs. Scala sources;

added content_length;

slightly more general Library.chunks;

misc tuning -- accumulate body via ListBuffer;

basic support for symbolic pretty printing; tuned;