infer_call_result can raise InferenceError so make sure to handle that for the call sites where it is used

infer_call_result started recently to raise InferenceError for objects for which it could not find any returns.
Previously it was silently raising a StopIteration, which was especially leaking when calling builtin methods.
Since it is after all an inference method, it is expected that it could raise an InferenceError rather than
returning nothing.

Close PyCQA/pylint#2350

The explicit StopIterations were themselves were cut in ceeee097.

pylint doesn't understand decorators

Empty generators and next calls within a generator without a default argument
now cause a cascade effect which results in a RuntimeError.

Close PyCQA/pylint#2317

Wrap the inference functions with raise_if_nothing_inferred where we didn't have any guards against them

This is especially important in a Python 3.7 worlds where we need to handle StopIteration
that can be triggered by next() over empty generators.

Close #596

Close #581

Close PyCQA/pylint#2267

Remove the copying of extra_context, since the object is already not mutated. Discovered during #588

This would introduce a new method of configuring astroid & pylint, while the
usual approach we used so far was to set a flag in the MANAGER itself it we'd
need to customize some behaviour (extension_package_whitelist and friends).

Also renamed the flag to `max_inferable_values` to be more suggestive on what it does.

spot performance issues.

Add new envrionment variable call ASTROID_MAX_INFERABLE to tune
the max inferable amount of values at a time.

Close #579
Close PyCQA/pylint#2251

See #581

Ignore non-string keys

Add context_lookup to the context class as extra_context.

Deliver the correct context with the correct boundnode
for function argument nodes.

Close #177

At the moment `load_from_module` is resolving all paths in `sys.path`
to validate that the module being import is in a folder part of the
path. This is done to resolve symlinks.

This can be an issue though it both the file being imported and the path
in `sys.path` resolve to different locations. Even if the symlinks are
importable, the resolution of the paths in `sys.path` might not.

The precedence and associativity rules of operators are respected
and parens are only wrapped around child nodes when needed

A single If node inside the else block is output as `elif`

Unneccesary parens in with statements are removed

Unneccesary parens in tuple returns are removed

Doc strings in classes and functions no longer get additional indenting

There's something going on with io/_io on PyPy. io has all its members coming from _io,
but _io's members themselves are also coming from _io, so astroid cannot find the actual
place where they are defined.