Restructuring of MethodSummary and SummaryGraph started with minimal
method bodies.
Some interim state to be saved.
FieldEdge added.
imports added.
New attributes added in print methods.
Type and attribute ReturnResult added that contains only object nodes,
field edges, and result values, and that can be merged from different
frames and return statements into one value for the exit point.
Printing out of method calls removed to keep the debug information
shorter.
toString() added.
printing out latest attributes.
Getters for RetunResult fields added.
Further development of restructured MethodSummary: c'tor is fed with
ReturnResult, global object graph is collapsed into singleton global
object, globally escaped objects are stored in separate object set.
MethodSummary.jrag simplified after part of the work has been moved into
new ReturnResult.