Add multilingual support in Hugo

Implements:
* support to render:
  * content/post/whatever.en.md to /en/2015/12/22/whatever/index.html
  * content/post/whatever.fr.md to /fr/2015/12/22/whatever/index.html
* gets enabled when `Multilingual:` is specified in config.
* support having language switchers in templates, that know
  where the translated page is (with .Page.Translations)
  (when you're on /en/about/, you can have a "Francais" link pointing to
   /fr/a-propos/)
  * all translations are in the `.Page.Translations` map, including the current one.
* easily tweak themes to support Multilingual mode
* renders in a single swift, no need for two config files.

Adds a couple of variables useful for multilingual sites

Adds documentation (content/multilingual.md)

Added language prefixing for all URL generation/permalinking see in the
code base.

Implements i18n. Leverages the great github.com/nicksnyder/go-i18n lib.. thanks Nick.
* Adds "i18n" and "T" template functions..

1 files changed, 6 insertions, 0 deletions

diff --git a/helpers/path.go b/helpers/path.go
index 0c18e5397..a8a50aab3 100644
--- a/helpers/path.go
+++ b/helpers/path.go
@@ -182,6 +182,12 @@ func GetThemeDataDirPath() (string, error) {
 	return getThemeDirPath("data")
 }
 
+// GetThemeI18nDirPath returns the theme's i18n dir path if theme is set.
+// If theme is set and the i18n dir doesn't exist, an error is returned.
+func GetThemeI18nDirPath() (string, error) {
+	return getThemeDirPath("i18n")
+}
+
 func getThemeDirPath(path string) (string, error) {
 	if !ThemeSet() {
 		return "", errors.New("No theme set")