Set translation domain implicitly in extensions

The translation team decided to store strings for extensions in different projects/domains than core, so extensions should not rely on the default "translation domain". When writing extension code that uses

{ts} or ts(), one must currently specify the "translation domain" as an extra argument. However, explicitly passing the domain with each invocation of {ts}

or ts() would be cumbersome and error-prone. We need a way to pass the domain in a more automatic fashion.

Below are some code-snippets discussed during the Dalesbridge sprint.

== Smarty example ==

{crmScope extensionKey="com.example.myext"}

{ts}

This is my string!

{/ts} {/crmScope}

== Javascript example ==

CRM.translate('com.example.myext', function(ts)

{ alert(ts('This is my string!')); });

== Javascript example (DEPRECATED) ==

CRM.extension('com.example.myext', [], function($, ts){ alert(ts('This is my string!')); }

);

== PHP example ==

• https://gist.github.com/totten/a2bac7904a4cfd9bb9bd (with namespaces – supported with civix codegen)
• https://gist.github.com/totten/2f3d4d6e6da5c2d3857b (with named instances – supported with new core class)