Balance changes and stuff!

Towers attack speed rework:

• Attack speed stat now increases 0.25 attacks per second (0.5 for laser ultimate) per point (instead of reducing the timer directly by a fixed amount, which resulted in very little increments at first, and exponentially growing until very big increments, so it didn't impact the early game, and it's too much at the latest points).

• Increase is linear now, not exponential.

• Max. attack speed remains the same: 10 attacks per second (20 for laser ultimate), but there's more total points required to reach max attack speed.

Towers attack damage:

• Towers don't gain free extra damage when they level up now.

• Attack damage increase value raised from 2 to 3 per stat point. After 7 points increase value raised by 1, after 15 points increase value raised by 4.

Upgrade Godot to 4.6.1.

New space map "Space New".

Small UI corrections.