Fix several memory leaks. (#3721)

Free results from g_file_get_path(), nemo_file_get_by_uri(),
nemo_file_get_display_name(), nemo_file_get_activation_uri(),
and g_settings_get_string() that were missing cleanup calls.

Co-authored-by: You name <konty@github.com>

nemo-file-operations.c: Fix file copies breaking ownership rules. (#3…

file operations: Fix some memory leaks.

Spotted by valgrind.

org.nemo.root.policy.in: Allow escalation for remote users.

ref: https://github.com/linuxmint/linuxmint/issues/629

nemo-list-view.c: Don't apply column-expand test unless there is

a drag operation active.

This test also affects clicking on the expander.