Persistent class + deepPersistent
Refactor according to comments.
Merge branch 'transientMap' of github.com:vacuumlabs/persistent into newData

Conflicts:
	lib/src/map.dart
	lib/src/persistent.dart
gitignore enhanced
Merge branch 'master' into vector
resize checks for negative index, fn with no return value
Merge branch 'vector' of github.com:vacuumlabs/persistent into vector
ReadVector interface
safe delete
VNode made private
rename asMutable,asImmutable to asTransient,asPersistent
renamed __ownerID to _owner
Merge branch 'transientMap' into vector
factor Owner to persistent.dart, use Owner from there in Vector, remove option references
Extracted ReadMap interface
rename all occurrences of mutable to transient
Merge branch 'transientMap' of github.com:vacuumlabs/persistent into transientMap

Conflicts:
	lib/src/map_impl.dart
Refactor test.
map implements Persistent
new randomized test for vector