Related to (closed) Issue #2094 on template inheritance. This PR adds a new function called "import" which works like "include", except it only takes one argument and passes it to the referenced file to be used as "." in that file.
* 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
// Imports the contents of another file and adds any template definitions to the template stack. If there are no defitions, the filepath will be the defition name. Any {{ define }} blocks will be accessible by {{ template }} or {{ block }}. Imports must happen before the template or block action is called
//
// **filename.html**
// ```
// {{ define "main" }}
// content
// {{ end }}
//
// **index.html**
// ```
// {{ import "/path/to/file.html" }}
// {{ template "main" }}
// ```
//
// ##### `include`
// ##### `include`
//
//
// Includes the contents of another file. Optionally can pass key-value pairs as arguments to be accessed by the included file.
// Includes the contents of another file and renders in-place. Optionally can pass key-value pairs as arguments to be accessed by the included file.
//
//
// ```
// ```
// {{include "path/to/file.html"}} // no arguments
// {{include "path/to/file.html"}} // no arguments