fix assertions in mut requirement check
correct unused import warnings
dataflow: correct for scopes exited on break, add debug printout
regionck: workaround issue around inferred type params
correct longstanding bug in region inference error  printouts
Patch up previous hack, invoke the custom visit_pat correctly for arms/locals
mass simplify and modernize ERROR comments
rustc: report borrows in const memory, correct handling of patterns, numerous tests
Be more careful about the order in which we read the next field
during task annihilation, since it is easy to tread on freed memory.
Add debug printouts to malloc/annihilation. These should get compiled
out unless you explicitly enable them when compiling.
wip: add borrowck-lend-flow test