feat(struct_tags): add range support (#117)

* feat(struct_tags): add range support

* refactor: use `start`, and `end_` naming for ranges

spec/fixtures/tags/add_range_input.go

@@ -0,0 +1,14 @@
+package main
+
+type Test struct {
+	ID      int
+	Name    string
+	Num     int64
+	Cost    int
+	Thingy  []string
+	Testing int
+	Another struct {
+		First  int
+		Second string
+	}
+}

spec/fixtures/tags/add_range_output.go

@@ -0,0 +1,14 @@
+package main
+
+type Test struct {
+	ID      int
+	Name    string `gopher:"name"`
+	Num     int64  `gopher:"num"`
+	Cost    int    `gopher:"cost"`
+	Thingy  []string
+	Testing int
+	Another struct {
+		First  int
+		Second string
+	}
+}

spec/fixtures/tags/remove_range_input.go

@@ -0,0 +1,14 @@
+package main
+
+type Test struct {
+	ID      int      `asdf:"id"`
+	Name    string   `asdf:"name"`
+	Num     int64    `asdf:"num"`
+	Cost    int      `asdf:"cost"`
+	Thingy  []string `asdf:"thingy"`
+	Testing int      `asdf:"testing"`
+	Another struct {
+		First  int    `asdf:"first"`
+		Second string `asdf:"second"`
+	} `asdf:"another"`
+}

spec/fixtures/tags/remove_range_output.go

@@ -0,0 +1,14 @@
+package main
+
+type Test struct {
+	ID      int      `asdf:"id"`
+	Name    string   `asdf:"name"`
+	Num     int64
+	Cost    int
+	Thingy  []string
+	Testing int      `asdf:"testing"`
+	Another struct {
+		First  int    `asdf:"first"`
+		Second string `asdf:"second"`
+	} `asdf:"another"`
+}