Bind TKLPatcher host apt cache to ISO patching process

During my time patching TKL ISOs one thing that has bugged me a bit when developing patches is downloading all those packages every time patches are applied. As a one off it's not that big a deal. But when I'm working on a patch and for one reason or another (usually because I forgot something, or something fails) I often end up applying the same patch a few times.

An easy solution to this has just occurred to me, and IMO it would have no negative impact on casual users of TKLPatch, and that is to mount --bind the host system /var/cache/apt/packages directory to the same within the temporary chroot filesystem (.rootfs). That way the downloaded packages would actually reside in the host system cache rather than destroyed when the patching process finishes. In my mind this mount would occur after extraction of the ISO and removed after the patch conf script had been applied.

The only potential for negative impact that I could imagine, would be were the systems not the same OS (ie if TKLPatch were installed to a non TKL/Ubuntu based system of the same version) although generally I would imagine that a smart packaging system such as apt would handle that ok.

Another thing for consideration would be, that 'apt-get clean' would no longer be relevant in patches (as long as the mount were removed prior to ISO reconstruction). If it were still included in a patch this would negate any advantage to this (because the host's cache would be cleaned).

I will have a play with this I think and see how it goes...