Add build.zig.zon, update build.zig, .gitignore

This adds a test running step and a zig.zon manifest.  Also adds to the
.gitignore the new location of caches, .zig-out.

Author: mnemnion

.gitignore

@@ -1 +1,2 @@
-zig-cache
+zig-*
+.zig-*

build.zig

@@ -1,7 +1,33 @@
 const std = @import("std");
 
 pub fn build(b: *std.Build) void {
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+
     _ = b.addModule("diffz", .{
         .root_source_file = b.path("DiffMatchPatch.zig"),
     });
+
+    const lib = b.addStaticLibrary(.{
+        .name = "diffz",
+        .root_source_file = b.path("DiffMatchPatch.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    // This declares intent for the library to be installed into the standard
+    // location when the user invokes the "install" step (the default step when
+    // running `zig build`).
+    b.installArtifact(lib);
+
+    // Run tests
+    const tests = b.addTest(.{
+        .name = "tests",
+        .root_source_file = b.path("DiffMatchPatch.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+    const step_tests = b.addRunArtifact(tests);
+
+    b.step("test", "Run diffz tests").dependOn(&step_tests.step);
 }

build.zig.zon

@@ -0,0 +1,11 @@
+.{
+    .name = "DiffMatchPatch",
+    .version = "0.0.1",
+    .paths = .{
+        "DiffMatchPatch.zig",
+        "LICENSE",
+        "README.md",
+        "build.zig.zon",
+        "build.zig",
+    },
+}