Use EXTERNAL-PROGRAM instead of TRIVIAL-SHELL; don't do symlinks (Librarian should work natively on Windows now).

darcs-hash:522e21c071fcecc499045c4ab2b6451ec8b64e22

darcs-hash:95b03a9cc2a2c2850ea0cff91829c0b3a53eab46

Drop systems/ dir, make bootstrap.sh download libs into new external/ subdir and link .asd files into Librarian's root dir.

darcs-hash:578ce1b81fbcbd47b422ee2a2ab55220eb5bdb53

darcs-hash:e433906d0a1abd458f70ac7cf93f4f24a8c94d5c

darcs-hash:cb98007ec7e76c84a5e822ddc2b2ab53e8b67a38

darcs-hash:7830aec8b244bcd502cc1cd7bb50476a4f792ab7

darcs-hash:d439497a59d5c55cc4c1ea4c40d9a75f0fd9aba2

darcs-hash:3143c28610e3b673ec00e8a5c051b7aef6711c2c

darcs-hash:02ecaa36bbb818ae204283e4cd95ad5586ada1c9

darcs-hash:5d6121437067026f2228cdd455aa930f677f1c1e

darcs-hash:24fdd6256877cdea5f10ac935eafd6072da09eb2

darcs-hash:cc545074422c9df51235e9beca08c7abeaaf442f