Add slack line calc

src/pages/tools/number/generic-calc/data/index.ts

@@ -2,5 +2,11 @@ import ohmslaw from './ohmsLaw';
 import voltageDropInWire from './voltageDropInWire';
 import sphereArea from './sphereArea';
 import sphereVolume from './sphereVolume';
-
-export default [ohmslaw, voltageDropInWire, sphereArea, sphereVolume];
+import slackline from './slackline';
+export default [
+  ohmslaw,
+  voltageDropInWire,
+  sphereArea,
+  sphereVolume,
+  slackline
+];