IDEA-171775 Missing JARs from repository library aren't downloaded when a library configuration is changed externally

project structure dialog: show warning if user tries to manually edit configuration of a library imported from an external model (IDEA-171948)

This information can be used to show a warning if user tries to manually change roots of a library imported from an external model in the Project Structure dialog (IDEA-171948). This information won't be saved in library configuration files until we implement functionality to store such libraries separately (and enable 'store.imported.project.elements.separately' registry key), because otherwise it would lead to massive changes in files under .idea/libraries.

It follows the behavior of the platform and IntelliJ IDEA in this regard.

restore hiding of completion hints after caret movement out of parameter list (broken after commit 7122ad8f)

- create copy file based on language

when the .getNavigationElement() is implemented to lead to a wildly different element (e.g. PsiPuppetVarWrapperImpl for "$mod" leads to a leaf element for identifier "mod"), correct the passed startOffset/endOffset accordingly to fix RUBY-19327 Variables names are partially highlighted in the Find Usages results

correct refresh after 'Toggle hints' action