System(s) Changes:
Optimized some stuff in Unit/Collective Rendering.
Added Overlay/Outline Rendering of Collectives (not just flags).
Added Drag-Select (much better user experience now since many units can be drag-selected at a time).
Moved big flag icon to the top left, so now the screen is a bit less cluttered.
Added Split Key (R) to deselect half of selected units (stopping at one unit selected).
Added new commands: "commander_attacks_for_player" and "commander_does_not_attack_for_player" to enable/disable AI sending player nation units to attack tiles when the AI is currently controlling the player's unit allocations via "hire_commander" (recall: "fire_commander" disables AI controlling player nation unit allocation altogether).
Added Unit Tile-Hop Cancellation/Override when giving new orders.
Added Cancel Order Key (X) to cancel the orders of all selected units and make them stop. This teleports units back to their current tile (a unit's current tile is only changed after they occupy their next tile), which should be fine for now.
Added All-Night, All-Day modes (Press O to toggle between All-Night and All-Day). Day/Night Cycle must be disabled via "P" key for these modes to be visible. By default, All-Night is active and the day/night cycle is disabled since it's aesthetically best in my opinion.
Bug Fixes:
Fixed Unit Teleportation.
Fixed all units freezing bug (it was an index-out-of-bounds error, so I made things a bit more error-proof).