Added version aliases: 6 -> 6.0, 7 -> 7.0 and 8 -> 8.0. The line:
using msvc : 6 ;
will configure detected version 6.0 but the condition will remain
'<toolset>msvc-6'.
Additionally the comment for the 'msvc.init' rule is updated.
Patch from Alexey Pakhunov.
[SVN r31192]
Vladimir Prus