Add tests and example for modpack support

Cargo.lock

@@ -17,6 +17,35 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "argh"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f023c76cd7975f9969f8e29f0e461decbdc7f51048ce43427107a3d192f1c9bf"
+dependencies = [
+ "argh_derive",
+ "argh_shared",
+]
+
+[[package]]
+name = "argh_derive"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "48ad219abc0c06ca788aface2e3a1970587e3413ab70acd20e54b6ec524c1f8f"
+dependencies = [
+ "argh_shared",
+ "heck",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "argh_shared"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38de00daab4eac7d753e97697066238d67ce9d7e2d823ab4f72fe14af29f3f33"
+
 [[package]]
 name = "autocfg"
 version = "1.0.1"
@@ -329,6 +358,15 @@ version = "0.11.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ab5ef0d4909ef3724cc8cce6ccc8572c5c817592e9285f5464f8e86f8bd3726e"
 
+[[package]]
+name = "heck"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6d621efb26863f0e9924c6ac577e8275e5e6b77455db64ffa6c65c904e9e132c"
+dependencies = [
+ "unicode-segmentation",
+]
+
 [[package]]
 name = "hermit-abi"
 version = "0.1.19"
@@ -1000,6 +1038,7 @@ dependencies = [
 name = "theseus"
 version = "0.1.0"
 dependencies = [
+ "argh",
  "bytes",
  "chrono",
  "daedalus",
@@ -1175,6 +1214,12 @@ dependencies = [
  "tinyvec",
 ]
 
+[[package]]
+name = "unicode-segmentation"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8895849a949e7845e06bd6dc1aa51731a103c42707010a5b591c0038fb73385b"
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.2"