Start populating mmc/mmc_hl_cmds.c. Create mmc directory in preparation

for making it a library.

mmc.h:  CDIO_MMC_GPCMD_ALLOW_MEDIUM_REMOVAL ->
        CDIO_MMC_GPCMD_PREVENT_ALLOW_MEDIUM_REMOVAL
mmc.c:  Move mm_eject_media and mmc_set_drive_speed to mmc/mmc_hl_cmds.c
mmc_ll_cmds.c: add mmc_prevent_allow_medium_removal,
               move mmc_mode_sense to mmc/mmc_hl_cmds.c

include/cdio/mmc_cmds.h

@@ -39,6 +39,17 @@
 extern "C" {
 #endif /* __cplusplus */
 
+  /**
+    Eject using MMC commands. If CD-ROM is "locked" we'll unlock it.
+    Command is not "immediate" -- we'll wait for the command to complete.
+    For a more general (and lower-level) routine, @see mmc_start_stop_unit.
+
+   @param p_cdio the CD object to be acted upon.
+   @return DRIVER_OP_SUCCESS (0) if we got the status.
+   return codes are the same as driver_return_code_t  
+  */
+  driver_return_code_t mmc_eject_media( const CdIo_t *p_cdio );
+  
   /**
     Return results of media status
 
@@ -114,6 +125,22 @@ extern "C" {
   driver_return_code_t  mmc_mode_sense_6( CdIo_t *p_cdio, /*out*/ void *p_buf, 
 					  unsigned int i_size, int page);
   
+  /**
+     Request preventing/allowing medium removal on a drive via 
+     SCSI-MMC PREVENT/ALLOW MEDIUM REMOVAL.
+
+     @param p_cdio the CD object to be acted upon.
+     @param b_prevent true of drive locked and false if unlocked
+     @param b_persisent make b_prevent state persistent
+
+     @return DRIVER_OP_SUCCESS (0) if we got the status.
+     return codes are the same as driver_return_code_t
+  */
+    driver_return_code_t 
+    mmc_prevent_allow_medium_removal(const CdIo_t *p_cdio, 
+				     bool b_persistent, bool b_prevent,
+				     unsigned int i_timeout_ms);
+    
   /**
       Issue a MMC READ_CD command.