use buffer 3.0.0

New Buffer major version: 3.0.0

It has some breaking changes, but they improve compatibility with node!
The whole node buffer test suite passes now, thanks to @jessetane!

- toString('ascii') and slice('ascii') work correctly (strip off high
order bits)
- correct exception types thrown (RangeError instead of TypeError in
many places)
- do not encode partial code units to utf16
- do not encode partial or invalid code points to utf8
- copy() correctly returns length
7.1.0
failing test case for identical deps from #1027
disable problematic style of deduping
passing identical different test
update dedupe tests for the new behavior
inline all changelogs
8.0.0
Don’t leak deduped path in row deps.

Fixes #951.
8.0.1
Ensure transforms execute in added order.
8.0.2
Allow requiring module locally and globally with `fullPaths=true`

This fixes #1020 in conjunction with `watchify` which uses `fullPaths=true`.
Consistently use default _options.basedir