Fix typo and clean up things

.idea/captcha.iml

@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="WEB_MODULE" version="4">
-  <component name="Go" enabled="true" />
-  <component name="NewModuleRootManager">
-    <content url="file://$MODULE_DIR$" />
-    <orderEntry type="inheritedJdk" />
-    <orderEntry type="sourceFolder" forTests="false" />
-  </component>
-</module>

.idea/modules.xml

@@ -1,8 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="ProjectModuleManager">
-    <modules>
-      <module fileurl="file://$PROJECT_DIR$/.idea/captcha.iml" filepath="$PROJECT_DIR$/.idea/captcha.iml" />
-    </modules>
-  </component>
-</project>

.idea/vcs.xml

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="VcsDirectoryMappings">
-    <mapping directory="$PROJECT_DIR$" vcs="Git" />
-  </component>
-</project>

captcha.go

@@ -74,9 +74,9 @@ type SetOption func(*Options)
 
 // Data is the result of captcha generation.
 // It has a `Text` field and a private `img` field that will
-// be used in `WriteImage` receiver
+// be used in `WriteImage` receiver.
 type Data struct {
-	// Text is captcha solution
+	// Text is captcha solution.
 	Text string
 
 	img *image.NRGBA
@@ -122,7 +122,7 @@ func LoadFontFromReader(reader io.Reader) error {
 }
 
 // New creates a new captcha.
-// It returns captcha data and any freetype drawing error encountered
+// It returns captcha data and any freetype drawing error encountered.
 func New(width int, height int, option ...SetOption) (*Data, error) {
 	options := newDefaultOption(width, height)
 	for _, setOption := range option {
@@ -143,7 +143,7 @@ func New(width int, height int, option ...SetOption) (*Data, error) {
 }
 
 // NewMathExpr creates a new captcha.
-// It will generate a image with a math expression like `1 + 2`
+// It will generate a image with a math expression like `1 + 2`.
 func NewMathExpr(width int, height int, option ...SetOption) (*Data, error) {
 	options := newDefaultOption(width, height)
 	for _, setOption := range option {

example/basic/main.go

@@ -2,9 +2,10 @@ package main
 
 import (
 	"fmt"
-	"github.com/steambap/captcha"
 	"html/template"
 	"net/http"
+
+	"github.com/steambap/captcha"
 )
 
 func main() {

example/load-font/main.go

@@ -2,10 +2,11 @@ package main
 
 import (
 	"fmt"
-	"github.com/steambap/captcha"
-	"golang.org/x/image/font/gofont/goregular"
 	"html/template"
 	"net/http"
+
+	"github.com/steambap/captcha"
+	"golang.org/x/image/font/gofont/goregular"
 )
 
 func main() {