"webconfig.py: Don't allow NoneType as buffer, fallback to bytes.
Fixes TypeErrors when using bindings tab"
Merge branch 'master' of github.com:fish-shell/fish-shell
Allow parse_util_detect_errors to treat incomplete strings as errors

Fixes bug where sourcing a file with an unclosed quote would not have a
backtrace
Avoid using OptionParser to parse bindings in webconfig.py

OptionParser eats commaandline arguments passed to bind actions, so avoid using it.
Add support for history --merge to incorporate history changes from
other sessions.

Fixes #825
Clean up default environment variables.

This stops unconditionally setting values for HOME and USER,
if we find those values in the environment. It also saves about 16KB
on OS X, which getpwuid allocates.
Make abbreviations work correctly with type-ahead

Fixes #1434