Do not delete type.
Only use one match stack for trie operations.
Fix problems with hash tables when using the tuple_search_iterators.
Merge branch 'master' into dev
Use expression optimization code in new compiler.
Merge commit 'c868d36027fe2af3f00d9e8b263b5715a539d93c' into flavio-dev

Conflicts:
	db/trie.cpp
	vm/program.cpp
Merge commit '47a5354454b59764e264d4b3af81827019f5e1fe' into flavio-dev

Conflicts:
	db/trie.cpp
	vm/exec.cpp
Merge commit 'dad0f2e9afa29ef258ae730c2ce1faf2a8e378bf' into flavio-dev
Merge commit '4726c4d4dc137558d584f93ca61c35283005632e' into flavio-dev

Conflicts:
	tests/code/neural_network1.m