modules/tests/Makefile.am: More thread sanitizer workaround.
engine/var: Filters no longer support regular expressions.  RNS-1065
engine/var.c: Fix bug in recent removal of filter regexps.
engine/core_tfns.c: String transformations now properly handle empty strings.  RNS-1069
util/bytestr.c: ib_bytestr_alias_mem() now properly handles empty strings. RNS-1069
lua/ironbee/waggle/base_rule.lua: Spelling fix.
predicate/standard_template.cpp: Fix bug in ref expansion. RNS-1069
predicate/tests/tc_predicate.rb: Add test of template transformation. RNS-1069
predicate/tests/test_merge_graph.cpp: Add test of MergeGraph knitting. RNS-1069
predicate/merge_graph.cpp: Fix corner case in remote_tree(). RNS-1069
predicate/merge_graph.cpp: Add roots to debug report.
predicate/merge_graph: Replace naive learning of changed ancestors to a knitting process that will properly merge ancestors that are now identical to other nodes. RNS-1069
predicate/merge_graph: Refactor some common code out into an update_root() function.
predicate/ibmod_predicate.cpp: Make assert valid always on.
predicate/tests/test_merge_graph.cpp: Fix knitting test.
engine/core_tfns.c: Fix urlDecode on empty strings.
transformations: Transformations that operate on byte strings should not error on zero-length byte strings.
predicate/functional.cpp: Remove redundant code.
util/string_trim.c: Fix bug with only whitespace input.  RNS-1072
Fix assert() errors reported by Andrei Belov

n.b. these are part of a wider problem of overuse of assert in place of
regular args/value checking