rm named error

Real version doesn't expose this

License: MIT
Signed-off-by: Brian Tiger Chow <brian@perfmode.com>
create wantlist object
give sessiongenerator a master context for easy cancelling
implement bitswap roundWorker

make vendor
extracted ledgerset from strategy, cleaned up a few comments from the PR
dont spawn so many goroutines when rebroadcasting wantlist
add priorities to GetBlocks requests, and add waitgroup to sendWantListTo
blockstore.ErrNotFound, and proper wantlist sorting