UI/installer: Specify "source" in plugins section

When using the full installer, there'll be a section where you can
choose what to install -- one section is a tree view with a "plugins"
section, and in that section there's "Browser plugin" and "Realsense
plugin".  Instead of superfluously saying "plugin" for each of those,
replace with "source" instead -- so browser source and realsense source.
Also somewhat helps prevent the user from getting confused and thinking
we're installing a browser or something.

UI/installer/mp-installer.nsi

@@ -273,7 +273,7 @@ SectionEnd
 
 !ifdef FULL
 SectionGroup /e "Plugins" SecPlugins
-	Section "Browser plugin" SecPlugins_Browser
+	Section "Browser Source" SecPlugins_Browser
 		; Set Section properties
 		SetOverwrite on
 		AllowSkipFiles off
@@ -292,7 +292,7 @@ SectionGroup /e "Plugins" SecPlugins
 	SectionEnd
 
 	!ifdef REALSENSE_PLUGIN
-	Section /o "Realsense plugin" SecPlugins_Realsense
+	Section /o "Realsense Source" SecPlugins_Realsense
 		SetOverwrite on
 		AllowSkipFiles off
 		SetShellVarContext all