Pull request i18n (#2804)

* ...

* ...

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* add translated files in Chinese.

* Remove compiled message files

* Consolidate translations into one set of files

* Rename .pot files to .po

* Add zh-CN to list of supported languages

* Ignore compiled .mo files

* Revert a couple of unimportant changes

.gitignore

@@ -6,6 +6,7 @@ docs/man/*.gz
 docs/source/api/generated
 docs/source/config.rst
 docs/gh-pages
+notebook/i18n/*/*.mo
 notebook/static/components
 notebook/static/style/*.min.css*
 notebook/static/*/js/built/

notebook/i18n/nbjs.json

@@ -1,6 +1,7 @@
 {
 	"domain": "nbjs",
 	"supported_languages": [
+		"zh-CN"
 	],
 	"locale_data": {
 		"nbjs": {