[564] Fix for absent RamFS icon on RISC OS 3
An old (version < 1.19) Switcher is patched when a theme is loaded in order to make the switcher icon name distinct. However, using *RMFaster to get a RAM copy to patch caused a problem that it now appears late enough in the module list that it's after all the resident filers and so never gets the Service_StartFiler call and so the machinery to restart RamFS' filer front end is ineffectual.
Fix this by instead using OS_Module 10 to insert the patched copy. This keeps the module list order, and so when the service call goes round Filer's task handle is successfully captured.
Tested on RISC OS 3.60.