Invert default "ensure newline" behaviour so that it is opt-in.

See #47.

coalesce_test.go

@@ -7,7 +7,7 @@ import (
 )
 
 func TestCoalesce(t *testing.T) {
-	lexer := Coalesce(MustNewLexer(&Config{DontEnsureNL: true}, Rules{
+	lexer := Coalesce(MustNewLexer(nil, Rules{
 		"root": []Rule{
 			{`[!@#$%^&*()]`, Punctuation, nil},
 		},

lexer.go

@@ -44,9 +44,9 @@ type Config struct {
 	// Strip all leading and trailing whitespace from the input
 	// StripAll bool
 
-	// Make sure that the input does not end with a newline. This
+	// Make sure that the input ends with a newline. This
 	// is required for some lexers that consume input linewise.
-	DontEnsureNL bool
+	EnsureNL bool
 
 	// If given and greater than 0, expand tabs in the input.
 	// TabSize int

lexers/make.go

@@ -11,6 +11,7 @@ var Makefile = Register(MustNewLexer(
 		Aliases:   []string{"make", "makefile", "mf", "bsdmake"},
 		Filenames: []string{"*.mak", "*.mk", "Makefile", "makefile", "Makefile.*", "GNUmakefile"},
 		MimeTypes: []string{"text/x-makefile"},
+		EnsureNL:  true,
 	},
 	Rules{
 		"root": {

mutators_test.go

@@ -44,7 +44,7 @@ func TestInclude(t *testing.T) {
 }
 
 func TestCombine(t *testing.T) {
-	l := MustNewLexer(&Config{DontEnsureNL: true}, Rules{
+	l := MustNewLexer(nil, Rules{
 		"root":  {{`hello`, String, Combined("world", "bye", "space")}},
 		"world": {{`world`, Name, nil}},
 		"bye":   {{`bye`, Name, nil}},

regexp.go

@@ -300,7 +300,7 @@ func (r *RegexLexer) Tokenise(options *TokeniseOptions, text string) (Iterator,
 	if options == nil {
 		options = defaultOptions
 	}
-	if !r.config.DontEnsureNL && !strings.HasSuffix(text, "\n") {
+	if r.config.EnsureNL && !strings.HasSuffix(text, "\n") {
 		text += "\n"
 	}
 	state := &LexerState{

remap_test.go

@@ -7,7 +7,7 @@ import (
 )
 
 func TestRemappingLexer(t *testing.T) {
-	var lexer Lexer = MustNewLexer(&Config{DontEnsureNL: true}, Rules{
+	var lexer Lexer = MustNewLexer(nil, Rules{
 		"root": {
 			{`\s+`, Whitespace, nil},
 			{`\w+`, Name, nil},