Trim only the separator key at end of path

Modifies https://github.com/karellm/i18next-parser/issues/11 to trim only separators at end of the path. Otherwise
```js
i18n.t("Loading...") 
```
With separator ':' turns into "Loading..".
Adapt tests to allow trailing dot with different separator

Adapts a test to the change 7fd10b5328f54d9eb407f8b1c3e122986ed84b36
Replace String.prototype.endsWith with String.prototype.indexOf

endsWith is not yet a standard
Fix test for trailing separator
Merge branch 'tobiasweibel-allow-trailing-dot'
Bump to 0.3.3