Improve package structure (#207)

* Improve package structure

* Set up travis

pkg/cli/utils/diff/diff.go

@@ -0,0 +1,48 @@
+/* Copyright (C) 2019 Monomax Software Pty Ltd
+ *
+ * This file is part of Dnote CLI.
+ *
+ * Dnote CLI is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Dnote CLI is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Dnote CLI.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+// Package diff provides line-by-line diff feature by wrapping
+// a package github.com/sergi/go-diff/diffmatchpatch
+package diff
+
+import (
+	"time"
+
+	"github.com/sergi/go-diff/diffmatchpatch"
+)
+
+const (
+	// DiffEqual represents an equal diff
+	DiffEqual = diffmatchpatch.DiffEqual
+	// DiffInsert represents an insert diff
+	DiffInsert = diffmatchpatch.DiffInsert
+	// DiffDelete represents a delete diff
+	DiffDelete = diffmatchpatch.DiffDelete
+)
+
+// Do computes line-by-line diff between two strings
+func Do(s1, s2 string) (diffs []diffmatchpatch.Diff) {
+	dmp := diffmatchpatch.New()
+	dmp.DiffTimeout = time.Hour
+
+	s1Chars, s2Chars, arr := dmp.DiffLinesToRunes(s1, s2)
+	diffs = dmp.DiffMainRunes(s1Chars, s2Chars, false)
+	diffs = dmp.DiffCharsToLines(diffs, arr)
+
+	return diffs
+}