rename bundle to archive throughout (mechanical change)
rename bundle to charm; rename receiver variables
rename Archive to CharmArchive etc
gofmt
rename Read to ReadCharm
Merge remote-tracking branch 'origin/master' into bundledata

Conflicts:
	charmdir.go
rename import paths
Merge branch 'rename-bundle-to-archive' of github.com:rogpeppe/charm into rename-bundle-to-archive
Merge pull request #8 from rogpeppe/rename-bundle-to-archive

charm: prepare for adding bundle support
charm: add BundleData, parser and Verify method.
add some more tests and comments as per review
Merge pull request #9 from rogpeppe/bundledata

charm: add BundleData, parser and Verify method.
charm: fix build.Import path
Merge pull request #10 from rogpeppe/001-fix-testing-charm-path

charm: fix build.Import path
charm: add VerifyWithCharms.

We don't yet verify the charm options. That will come later.
charm: adjust verifyRelation comment for review
Merge pull request #11 from rogpeppe/002-bundle-external-validation

charm: add VerifyWithCharms.
charm: change VerifyWithCharms to check charm options.

We also change it so that it takes a map[string]Charm
so it has access to the charm metadata. Strictly speaking,
that's more info than it needs (it doesn't use the charm
actions) but we think the API cleanliness makes it worthwhile.
charm: fix comments so they don't imply that verification order is important
Merge pull request #12 from rogpeppe/003-bundle-check-options

charm: change VerifyWithCharms to check charm options.