Add SQLite support, fix un-thread-safe DB caches, small performance f… (#172)

* Add SQLite support, fix un-thread-safe DB caches, small performance fixes

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

* add SQLite licenses to README

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

* appease the linter, and fix my dumbass-ery

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

* make requested changes

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

* add back comment

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

internal/cache/status_test.go

@@ -0,0 +1,41 @@
+package cache_test
+
+import (
+	"testing"
+
+	"github.com/superseriousbusiness/gotosocial/internal/cache"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+func TestStatusCache(t *testing.T) {
+	cache := cache.NewStatusCache()
+
+	// Attempt to place a status
+	status := gtsmodel.Status{
+		ID:  "id",
+		URI: "uri",
+		URL: "url",
+	}
+	cache.Put(&status)
+
+	var ok bool
+	var check *gtsmodel.Status
+
+	// Check we can retrieve
+	check, ok = cache.GetByID(status.ID)
+	if !ok || !statusIs(&status, check) {
+		t.Fatal("Could not find expected status")
+	}
+	check, ok = cache.GetByURI(status.URI)
+	if !ok || !statusIs(&status, check) {
+		t.Fatal("Could not find expected status")
+	}
+	check, ok = cache.GetByURL(status.URL)
+	if !ok || !statusIs(&status, check) {
+		t.Fatal("Could not find expected status")
+	}
+}
+
+func statusIs(status1, status2 *gtsmodel.Status) bool {
+	return status1.ID == status2.ID && status1.URI == status2.URI && status1.URL == status2.URL
+}