Add name substitution to shader templates and improve template structure

Co-authored-by: neph1 <[email protected]>

jme3-materialeditor/src/com/jme3/gde/materialdefinition/BasicShader.frag

@@ -1,3 +1,4 @@
+// Fragment shader for ${name}
 uniform vec4 m_Color;
 
 void main(){

jme3-materialeditor/src/com/jme3/gde/materialdefinition/BasicShader.vert

@@ -1,3 +1,4 @@
+// Vertex shader for ${name}
 uniform mat4 g_WorldViewProjectionMatrix;
 
 attribute vec3 inPosition;