Rethink the extension script building

[robe]

Right now the postgis sql files included in extension are hardcoded. This is what caused the break at #2356.

At some point we'll need to variablize this based on version we are at so changes like this don't easily break the extension build. Testing extensions would help too.

We also may have issues when there is a difference between minor and micro upgrades. right now the same script is used for all upgrades.

[strk]

I made it so minor and micro will always be the same script. Sounds better now ? Does it resolve this ?

[robe]

I think so. I'll test later this week (probably over weekend) with upgrading from 2.0-2.1 2.0-2.2 , 2.1-2.2, 2.1.1 - 2.1.2 dev and see if I run into any issues. I'll close this out if all looks good.

[robe]

I think this is fine.