rework mod

* register armor using `armor:register_armor` (fixes #4)
* improve code readability
* make `technic_worldgen` optional
* add screenshot
* update readme and mod.conf
* remove integration test (unnecessary for a simple mod)
* remove other unnecessary files

.github/workflows/integration-test.yml

@@ -1,13 +0,0 @@
-name: integration-test
-on: [push, pull_request]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@master
-
-    - name: integration-test
-      run: ./integration-test.sh

.github/workflows/luacheck.yml

@@ -1,11 +1,8 @@
-name: build
+name: luacheck
 on: [push, pull_request]
-
 jobs:
   build:
-
     runs-on: ubuntu-latest
-
     steps:
     - uses: actions/checkout@master
     - name: apt