fixes #23

sometimes it is possible to manually fix the problem, for example mount
the alpine device manually after modprobing the correct modules. Then it
makes sense to continue boot rather than just die.

set default packages dir to ~/packages

fixes #22

prefix a makedepends with ! and its treated as a conflict. for example:

makedepends="zlib-dev !gettext"

check if wget is in makedepends.

fixes #11

I think we only need raid1 and maybe raid5 but now we copy the entire md
subdir. so there are room for size optimization here.

use 'make iso' to build the iso image.

This is because we might want to build for usb

This will hopefully fix the checksum errors

install scripts are splitted into separate scripts. The install variable
should contain a list of the scripts. Each script should be the pkgname with
action as suffix. I.E:

install="$pkgname.pre-install $pkgname.post-install"