Add read-only mode for files
When importing a file in pseuCo.com, it is presented in a read-only mode. To edit it, it must be saved locally first.
As discussed with @fefrei, the IDE should mimic this behaviour: Currently, when a file is imported, it is directly written to the disk, such that it can be edited. This should be postponed until the user decides to do so, while it remains possible to only view and execute the file (possibly placed in a temporary location, as a proper file is required by the compiler). Afterwards, the file can be edited as before.