Graphics contribution (icons, shadow, map icon, technology...)

[snouz]

Hi wolfhowlmedia/twilightthepony !

I've made a (mostly graphical) contribution to this great mod, you can see my changes here:

- New (hd) icons (technologies, items, equipment).
- Shifting shadow to the right as helicopter rises (like other entities).
- Added custom map icon.
- New mod icon.
- Helicopter is slightly more contrasted.
- Centered alert icon.
- Optimized PNG to gain space. (For info, compression was done losslessly with PNGGauntlet)

For info, I've been modding for almost a year now, and contributed to a good number of mods, so I don't think I've broken anything, but if something isn't at your taste, feel free to ask me to change it !

My mod page: https://mods.factorio.com/mod/MbrTestMod