typo fixes

Change-Id: I735005f2e311abf7b64cce6b67002fe6e0d60281
.git can be a directory, too, in submodules

Change-Id: I19367f168be1f2fa79d7e52915ab0269345b728c
it is helpcontent2, not helcontent2

Change-Id: Ia12efd8f69f32db29a84d4d9c94c179e1b3716a3
set correct git archive prefix

Change-Id: Ieb58119c8c33277ef8cf1e8bc8afeff5c7c547f4
xz instead of zx

Change-Id: Ifcf95b2e2bc3eb6df8ec3a558ebac25154c1493a
--core-dir is not implemented

Change-Id: Id12c36b6fc28f89e9e9d1aaedad5dc4f1a216313
generate source tarballs for Debian/Singularity

Change-Id: Ic037654465d9286ecfa054319ebe49ddd87b5284