elsarticle.layout: force plain layout for some flex insets

- This prevents LaTeX errors because some commands don't allow to include commands.
- also simplified some code

lib/layouts/elsarticle.layout

@@ -103,6 +103,7 @@ End
 InsetLayout "Flex:Titlenotemark"
 	LyxType		custom
 	LatexType	command
+	ForcePlain	1
 	LatexName	tnoteref
 	LabelString	"Titlenote mark"
 	Font
@@ -171,6 +172,7 @@ End
 InsetLayout "Flex:Authormark"
 	LyxType		custom
 	LatexType	command
+	ForcePlain	1
 	LatexName	fnref
 	LabelString	"Author mark"
 	Font
@@ -202,23 +204,11 @@ End
 
 
 InsetLayout "Flex:CorAuthormark"
-	LyxType		custom
-	LatexType	command
+	CopyStyle	"Flex:Authormark"
 	LatexName	corref
 	LabelString	"CorAuthor mark"
-	Font
-	  Color		foreground
-	  Size		Small
-	  Family	Roman
-	  Shape		Up
-	  Series	Medium
-	  Misc		No_Emph
-	  Misc		No_Noun
-	  Misc		No_Bar
-	EndFont
 	LabelFont
 	  Color		blue
-	  Size		Small
 	EndFont
 End