Refine log regarding attaching images to BIOS & IDE

[maron2000]

Add some information in logs when disk images are mounted, so that users can be aware of missing drives in BIOS or IDE especially when booting a guest OS.
Also, changed logging of keyboard flush to log only when user specifies to do so.

Examples of logs mounting one CD image and four hard drive images are shown below.
Since there are five images to attach to respective IDE slots, but by default there is only four (1m,1s,2m,2s) so log shows that you don't have enough slots.
Of course if you enable the tertiary controller, there will be no warnings.

LOG: IDE: WARNING Trying to attach image to IDE Tertiary controller but not available.  <- added
LOG: IMGMOUNT: CD-ROM image mounted to drive D (IDE Secondary Master) <- amended (previosly IDE: index 1 slave 0) 
LOG: FAT: Partition type is MBR (IBM PC)
LOG: Mounted FAT volume is FAT16 with 40742 clusters
LOG: Mapping BIOS DISK C/H/S 650/2/63 as IDE 650/2/63
LOG: IMGMOUNT: HDD image mounted to drive no. 2 (IDE Primary Master) <- amended
LOG: FAT: Partition type is MBR (IBM PC)
LOG: Mounted FAT volume is FAT16 with 40742 clusters
LOG: Mapping BIOS DISK C/H/S 650/2/63 as IDE 650/2/63
LOG: IMGMOUNT: HDD image mounted to drive no. 3 (IDE Primary Slave) <- amended
LOG: FAT: Partition type is MBR (IBM PC)
LOG: Mounted FAT volume is FAT16 with 40742 clusters
LOG: Mapping BIOS DISK C/H/S 650/2/63 as IDE 650/2/63
LOG: IMGMOUNT: HDD image mounted to drive no. 4 (IDE Secondary Slave) <- amended
LOG: FAT: Partition type is MBR (IBM PC)
LOG: Mounted FAT volume is FAT16 with 41631 clusters
LOG: IDE: WARNING: IDE controller Secondary Master already occupied, specify another slot. <- added