patchbomb: add --body flag to send patches as inline message body text There is currently no way to make patchbomb include patches both as attachments and as inline text. This would be quite convenient when sending patches to people who use web email clients (e.g. gmail) which often mangle the patches, making them hard to apply. The default behavior of the email command is unchanged. However it is now possible to use the --body flag _in addition_ to the -i or -a flags, in which case the patchbomb emails will contain the patch as inline body text and as an attachment. A new test has been added to test-patchbomb.t ("test attach for single patch"), based on the existing test called "test attach for single patch" test.