Replace concrete filesystem usage with interface

Author: Galaco

go.mod

@@ -15,5 +15,5 @@ require (
 	github.com/go-gl/mathgl v0.0.0-20190713194549-592312d8590a
 	github.com/golang-source-engine/filesystem v0.1.2
 	github.com/golang-source-engine/stringtable v0.1.0
-	github.com/golang-source-engine/vmt v0.1.0
+	github.com/golang-source-engine/vmt v0.1.1
 )

go.sum

@@ -43,6 +43,8 @@ github.com/golang-source-engine/vmt v0.0.0-20190917225430-668305ff2fd8 h1:jBRzeb
 github.com/golang-source-engine/vmt v0.0.0-20190917225430-668305ff2fd8/go.mod h1:NVdf67X6t/Uu2WsOIyVNMJPGR9DIhBJMqrU2rpJlqQM=
 github.com/golang-source-engine/vmt v0.1.0 h1:B9RVSozvfgnfK0FWao/XPgf83FVIByeMeQNm5onInU8=
 github.com/golang-source-engine/vmt v0.1.0/go.mod h1:bXMpaO+WnKcuJ+CyR8sgrKnxQ+2+13OribIL+pgZmeg=
+github.com/golang-source-engine/vmt v0.1.1 h1:yBl2XzwBhmwmpEWxEK5t7HpfL63ZTOwGcEMsA/xUrTc=
+github.com/golang-source-engine/vmt v0.1.1/go.mod h1:devs1P7sA/Spthvxw8+wzuEsN3Ibadbia6n3SQQfdW8=
 github.com/logrusorgru/aurora v0.0.0-20190428105938-cea283e61946 h1:z+WaKrgu3kCpcdnbK9YG+JThpOCd1nU5jO5ToVmSlR4=
 github.com/logrusorgru/aurora v0.0.0-20190428105938-cea283e61946/go.mod h1:7rIyQOR62GCctdiQpZ/zOJlFyk6y+94wXzv6RNZgaR4=
 golang.org/x/image v0.0.0-20190209060608-ef4a1470e0dc/go.mod h1:ux5Hcp/YLpHSI86hEcLt0YII63i6oz57MZXIpbrjZUs=

loader/material/common.go

@@ -0,0 +1,7 @@
+package material
+
+import "io"
+
+type VirtualFilesystem interface {
+	GetFile(string) (io.Reader, error)
+}

loader/material/vmt.go

@@ -1,11 +1,10 @@
 package material
 
 import (
-	"github.com/golang-source-engine/filesystem"
 	"github.com/golang-source-engine/vmt"
 )
 
-func LoadVmtFromFilesystem(fs *filesystem.FileSystem, filePath string) (*vmt.Properties, error) {
+func LoadVmtFromFilesystem(fs VirtualFilesystem, filePath string) (*vmt.Properties, error) {
 	mat,err := vmt.FromFilesystem(filePath, fs, vmt.NewProperties())
 	if err != nil {
 		return nil, err