* Update tplcontext.go
Add {{ render "/path/to/file.ext" $data }} via funcRender
* Update tplcontext.go
* Refactor funcInclude, add funcImport to enable {{block}} and {{template}}
* Fix funcImport return of nil showing up in html
* Update godocs for and
* Add tests for funcInclude
* Add tests for funcImport
* os.RemoveAll -> os.Remove for TestFuncInclude and TestFuncImport