IDEA-132912
Toggle buttons ignore ''Show Classes'' in Override Methods dialog
infer method nullity by dfa (to use in extract method refactoring)
PY-14331 Do not show excluded folders in import completion
PY-14595 Handle namespace packages when updating imports for moved symbol

I added new method PyUtil#turnDirIntoPackageElement, that unlike
PyUtil#turnDirIntoInit is aware about namespace packages and return
passed directory itself in this case. Not sure, that altering
behavior of #turnDirIntoInit is a good idea, because its name will be
confusing then.
#WEB-7236 fixed
allow disabling browser hover in editor
#WEB-461 fixed
cleanup
fix NPE in notification on IOError
#WEB-14085 fixed
disable deep parameter delete for super calls only
infer nullity: do not suggest @Nullable/@NotNull based on lambda return statements inside
invert boolean: skip lambda returns
extract method object: do not touch return statements in nested lambdas
remove private constructor
add utility class to work with tabbed content
equals/hashCode based on VirtualFile
refactor History tab management. Use ContentUtilEx
IDEA-133329 Settings: second-level dialog uses big error message from the main Settings dialog