add {{#obj:key}} object iteration
add {{#obj:key}} object iteration

Allows iteration over objects instead of just arrays, activated by using a placeholder name on the section tag, prefixed by ":".
Inside the section, the key as a tag will equal the name of the object property's key.
`Mustache.to_html("{{#a:key}}{{key}}={{.}} {{/a:key}}", {a:{b:1,c:2}}) === "b=1 c=2 " `
rndme/mostache