docs: Minor typo fix

* docs/editing.rst: s/occurence/occurrence
Merge pull request #299 from theanalyst/fix/typo

docs: Minor typo fix
Use multiline strings in test code
Add "rename in superclass" and "replace in strings" option to rename

Rope supports renaming methods and members in the complete hierarchy.

For example, in the following

  class A(object):
    def foo(self): pass

  class A2(A):
    def foo(self): pass

We want to be able to rename A2's foo as well as A's foo at the same
time.

Rope supports this as "in_hierarchy" so add it to the rename dialog.

Also, rope allows to change occurences in strings and docstrings, let
the user choose whether he wants that as well.
Fix some PEP8 warnings in the refactoring change.
Add and use assertSourceEqual in refactor test cases.
Use print function, not statement, for Python 3 compatibility.
updated yasnippet variable 'text' to 'yas-text'
Merge pull request #311 from danielwuz/fix_snippet

updated yasnippet variable 'text' to 'yas-text'
Do not override company-backend for a call to dabbrev.

Overriding company-backend like this seems to have confuse company
at times, leading to the current backend being set to nil. Do not
let-bind the backend anymore, simply return the results of dabbrev
and tell company that we can have duplicates.

The latter reduces some performance, though.

Addresses #298.
Increase RPC timeout in tests.

Travis regularly is lagging out for a 1 second timeout. Bump it up
to 10 seconds.
Ensure that Rope won't re-check the whole project directory.

The previous hack did not take into account us calling validate(),
thereby throwing away our carefully-crafted file list. We now fully
replace the FileListCacher.

Addresses #309.
Update NEWS.rst for v1.5.1, and mention updating NEWS.rst in RELEASE.txt.

I keep forgetting that.
Add comments to indicate which Rope bugs we're testing for.
doc: add missing dot
Merge pull request #313 from tshepang/patch-1

doc: add missing dot
Rope backend now uses a central call interface.

Most calls to Rope follow similar call signatures and need to catch
the same exceptions. Factor out all of this into a common function
similar to the Jedi backend.
Show the current flymake error in the echo area.

When the current line is highlighted by flymake, Elpy will now
display the flymake error for that line instead of the function
call signature.

Fixes #232.
Multiedit now works correctly in buffers without files.

The backend can return nil/None/null as a file name, which is now
interpreted as referring to the current file.

Fixes #305.
Rope will not error when the project root is missing.

It was possible, especially in tramp buffers, for Elpy to initialize
Rope with an inexisting project root. This would make Rope throw
an error. We now initialize Rope with the empty string as the project
root.

I'm not sure if the empty string is the best option, but Rope does
not like None, and at this point, we have no better option, really.

Fixes #319.