refactor(Core): Remove Core from exposed api

BREAKING CHANGE: Since the full potential of core is now exposed through the default
translationManager, it is no longer necessary to expose this method

Author: Gertjan Reynaert

src/index.js

@@ -1,6 +1,5 @@
 export { default } from './manageTranslations';
 
-export { default as core } from './core';
 export { default as readMessageFiles } from './readMessageFiles';
 export { default as createSingleMessagesFile } from './createSingleMessagesFile';
 export { default as getDefaultMessages } from './getDefaultMessages';