Externalize spec typings, use eslint.

Tslint is deprecated, as such we have moved to eslint. Linted the project with more
stringent rules. The configuration will be changed as we figure out which rules we
should keep.

src/util/VersionSegmentedRegistry.ts

@@ -2,6 +2,8 @@ import { ForgeModStructure113 } from '../model/struct/model/module/forgemod/forg
 import { ForgeModStructure17 } from '../model/struct/model/module/forgemod/forgemod17.struct'
 import { Forge113Adapter } from '../resolver/forge/adapter/forge113.resolver'
 import { Forge17Adapter } from '../resolver/forge/adapter/forge17.resolver'
+import { ForgeResolver } from '../resolver/forge/forge.resolver'
+import { BaseForgeModStructure } from '../model/struct/model/module/forgemod.struct'
 
 export class VersionSegmentedRegistry {
 
@@ -20,7 +22,8 @@ export class VersionSegmentedRegistry {
         forgeVersion: string,
         absoluteRoot: string,
         relativeRoot: string,
-        baseURL: string) {
+        baseURL: string
+    ): ForgeResolver {
         for (const impl of VersionSegmentedRegistry.FORGE_ADAPTER_IMPL) {
             if (impl.isForVersion(minecraftVersion)) {
                 return new impl(absoluteRoot, relativeRoot, baseURL, minecraftVersion, forgeVersion)
@@ -34,7 +37,7 @@ export class VersionSegmentedRegistry {
         absoluteRoot: string,
         relativeRoot: string,
         baseUrl: string
-    ) {
+    ): BaseForgeModStructure {
         for (const impl of VersionSegmentedRegistry.FORGEMOD_STRUCT_IML) {
             if (impl.isForVersion(minecraftVersion)) {
                 return new impl(absoluteRoot, relativeRoot, baseUrl)