[READY] Update Python documentation and add extra conf file
This PR updates the Python docs and adds a `.ycm_extra_conf.py` file to be able to complete third-party packages in YCM code.
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[READY] Support modifiers for GoTo commands
This PR allows users to customize how a window is split when running the `GoTo*` commands by prefixing them with the modifiers `:aboveleft`, `:belowright`, `:botright`, etc. (see `:h mods` for the complete list). For instance, to split a window vertically at the right of the screen, one could do:
```viml
:botright vertical YcmCompleter GoTo
```
The `'horizontal-split'` and `'vertical-split'` values of the `g:ycm_goto_buffer_command` option are replaced by `'split'` since a vertical split can be obtained by prefixing the `:vertical` modifier. Those values are still kept for backward compatibility.
A new value is added `'split-or-existing-window'` that is equivalent to `new-or-existing-tab` when the `:tab` modifier is used. Without the `:tab` modifier, the `GoTo*` commands only jump to an existing window if that window is in the current tab page.
Closes https://github.com/Valloric/YouCompleteMe/pull/3090.
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Java completer can include FixIts which are applied when a completion
entry is selected. We use the existing mechanism implemented for c-sharp
to perform these edits using the CompleteDone autocommand.
However, the existing mechanism relies on pattern matching the source to
work out which item was completed. Vim patch 8.0.1493 introduces support
for user_data on completion items, so when available we populate it with
the completion array index of the item and use that to get the exact
element that was selected. This is both a lot faster and a lot more
accirate.
Of course when applying these 'FixIts' we don't interrupt the user with
confirmation or the quickfix list as this would just be annoying. If the
server reports that an edit must be made, we just make the edit. This is
achieved by adding a silent flag to ReplaceChunks.
When no argument is given to the YcmToggleLogs command, instead of displaying
the list of available logfiles, prompt the user to open (or close if already
open) one of them.
Do not call user's completion function if the start column is after the current
column or if there are no candidates. This avoids keeping the user in
completion mode even if there is no completion menu.
