standardized String.concat towards implode (cf. c37a1f29bbc0)

adding quickcheck examples for evaluating floor and ceiling functions

adding code equations to execute floor and ceiling on rational and real numbers

adding a floor_ceiling type class for different instantiations of floor (changeset from Brian Huffman)

inner syntax supports inlined YXML according to Term_XML (particularly useful for producing text under program control); tuned signature;

lambda terms with XML data representation in Scala; avoid `class` in signature;

XML data representation of lambda terms;

YXML.string_of_body convenience;

made SML/NJ happy;

tuned signature;

more abstract signature; tuned;

simplified XML_Data;

less currying in Scala;

propagate header changes to prover process; simplified Document case classes; Document.State.assignments: indexed by Version_ID;

echo prover input via raw_messages, for improved protocol tracing;

tuned;

tuned signature;

clarified propagation of node name and header;

more precise treatment of prover definedness;

tuned source structure;

some support for blobs (arbitrary text files) within document nodes;

tuned signature;

moved global state to structure Document (again);

moved Outer_Syntax.load_thy to Thy_Load.load_thy; tuned signatures; tuned module dependencies;

less stateful outer_syntax;

discontinued odd Position.column -- left-over from attempts at PGIP implementation; Position.offset discriminates postions precisely, now also available for Position.line/line_file;

discontinued special treatment of hard tabulators;

eliminated hard tabs;

merged

merged