Fix Params case handling in the index, sort and where func

This means that you can now do:

```
{{ range where .Site.Pages "Params.MYPARAM" "foo" }}
```

2 files changed, 7 insertions, 2 deletions

diff --git a/resources/resource/params.go b/resources/resource/params.go
index 4cb41715d..89da718ec 100644
--- a/resources/resource/params.go
+++ b/resources/resource/params.go
@@ -19,12 +19,16 @@ import (
 	"github.com/spf13/cast"
 )
 
-func Param(r ResourceParamsProvider, fallback map[string]interface{}, key interface{}) (interface{}, error) {
+func Param(r ResourceParamsProvider, fallback maps.Params, key interface{}) (interface{}, error) {
 	keyStr, err := cast.ToStringE(key)
 	if err != nil {
 		return nil, err
 	}
 
+	if fallback == nil {
+		return maps.GetNestedParam(keyStr, ".", r.Params())
+	}
+
 	return maps.GetNestedParam(keyStr, ".", r.Params(), fallback)
 
 }
diff --git a/resources/resource/resourcetypes.go b/resources/resource/resourcetypes.go
index 7a055b25d..b525d7d55 100644
--- a/resources/resource/resourcetypes.go
+++ b/resources/resource/resourcetypes.go
@@ -14,6 +14,7 @@
 package resource
 
 import (
+	"github.com/gohugoio/hugo/common/maps"
 	"github.com/gohugoio/hugo/langs"
 	"github.com/gohugoio/hugo/media"
 	"github.com/gohugoio/hugo/resources/images/exif"
@@ -85,7 +86,7 @@ type ResourceMetaProvider interface {
 
 type ResourceParamsProvider interface {
 	// Params set in front matter for this resource.
-	Params() map[string]interface{}
+	Params() maps.Params
 }
 
 type ResourceDataProvider interface {