Tech Tier Numbers on Tech Icons (2.1)

For Stellaris 2.1.x only.
For newer stellaris versions, see "Tiered numbers for techs" mod here:
https://steamcommunity.com/sharedfiles/filedetails/?id=2024528246

Adds tech tier number to many similar-looking technology icons for linear ship and building upgrades like ship reactors, thrusters, mine/farm/lab tiers, etc.
Only overrides dds icon files, should be compatible with acheivements and all mods, does not affect multiplayer compatibility, can be added/removed at any time.

Based on @Peter34's suggestion in Tech Tier Numbers on Laser Icons mod comments to do same thing for other tech icons.
(no need to install both btw, as this one includes all laser tech icons as well)

Might not affect absolutely all linear research paths, as I did focus on picking techs that unlock straight-up upgrades, with few others having tier number right in the icon names mixed-in.
If something obvious and/or confusing is missing or something is mislabelled - let me know in the comments, it's trivial to add/remove these overlays.

Note that mods can potentially change ordering of tech tiers, so that numbers on icons won't correspond to new order exactly, though I haven't bumped into any mods that do that myself - most seem happy to either leave vanilla technologies intact or remove/replace whole tech trees.

Number overlays (produced from armor icons by subtracting template background) are included in the zip under gfx-icon-templates directory and can be applied on top of any other tech via e.g. "convert -composite -gravity center mytech_1.png tech_n_1.png mytech_1.png" command (ImageMagick tool).