debian: Rename debian directory to debtpl (fixes #3099)

To keep it out of the way for actual, real, Debian packagers

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3195

.gitignore

@@ -1,7 +1,4 @@
-syncthing
-!gui/syncthing
-!debian/syncthing
-!Godeps/_workspace/src/github.com/syncthing
+/syncthing
 syncthing.exe
 *.tar.gz
 *.zip

build.go

@@ -438,7 +438,7 @@ func buildDeb(target target) {
 		"date":    time.Now().Format(time.RFC1123),
 	}
 
-	debTemplateFiles := append(listFiles("debian/common"), listFiles("debian/"+target.name)...)
+	debTemplateFiles := append(listFiles("debtpl/common"), listFiles("debtpl/"+target.name)...)
 	for _, file := range debTemplateFiles {
 		tpl, err := template.New(filepath.Base(file)).ParseFiles(file)
 		if err != nil {