Fix OmniSharp launch under Windows
Small refactoring

Use the dedicated function to check if we're running on Windows instead
of checking the platform directly.
Fix faulty logic in previous commit

Previous commit is 9b8781322ef3d18430c3da37e9d6b1be3b832f8b
Fixed OmniSharp launch under Windows (again)

We pass shell=True to Popen so that OmniSharp is not started inside a
new visible window under Windows. And since we use shell=True, we pass
the command to execute as a string, as recommended by Python's docs
(also, it won't work when passed as a sequence anyway :) ).
Removed an unused import
Small stylistic change
New wrapper function around subprocess.Popen

New wrapper function around subprocess.Popen that handles stdin
correctly when on Windows (see issue #637)
Check for libc++ before using it.

Fixes #731.
Changed HEAD of third_party/argparse (Create gitignore file).
Merge pull request #736 from dzhioev/master

Changed HEAD of third_party/argparse (Create gitignore file).
Try to cleanup files only if they stil exist

Fixes #738
Better handling of unknown extra conf files

Previously, we'd implicitly turn off future notices about unknown extra conf
files if we already raised one exception about it. This breaks when the user
ends up not receiving the "unknown extra conf, load?" message.

Now we only turn off the notice as a result of the user saying "don't load this"
so that if the first request fails to reach them, they'll get a second (and
third etc) request about it.

Fixes #615
Changed HEAD of third_party/frozendict (Create gitignore file).

This commit gets rid of annoying "modified: third_party/frozendict
(untracked content)" git status when *.pyc file was created inside
third_party/frozendict.
Merge pull request #745 from dzhioev/master

Changed HEAD of third_party/frozendict (Create gitignore file).
Merge branch 'fix-omnisharp-launch' of https://github.com/nop00/YouCompleteMe into nop00-fix-omnisharp-launch
Forwarding args for SafePopen to Popen directly
Revert "Not using Syntastic lazy redraw anymore"

This reverts commit 4d8fea4b2d29d89a7c3efc3eab0f0fd46cbc0645.

Since the commit we are reverting didn't resolve #669, we are reverting it to
fix #593 (again).
Preventing traceback for detailed diagnostic

Previously we'd show a Python traceback if the user asked for a detailed
diagnostic in a file that wasn't supported by Clang (something written in Python
perhaps). Now we show an nice, far less scary message informing the user of
this.

Fixes #748.
Handling vim.error from omnifunc

If the omnifunc encounters a syntax error, we need to handle this without
showing a traceback to the user.
Adding more include paths to YCM's ycm_extra_conf