rstream: Initialize 'rstream' field in RBuffer class

This field is used in a conditional jump, so this initialization is fixing a
bug.
rstream: Add rbuffer_read_ptr/rbuffer_write_ptr functions

rbuffer_data was renamed to rbuffer_read_ptr, and it represents the next read
position in a RBuffer instance. Similarly, rbuffer_write_ptr was added to
represent the next write position.

Also, rbuffer_data was being used for writing(in alloc_cb), replace that by
rbuffer_write_ptr.
Merge PR #1306 'RBuffer fixes'
Improve YCM contrib: Fix 'no newline at end of file' issue.

Problem:  YCM was reporting a much disturbing warning about a missing
          newline at the end of some files. This was odd, as the
          newlines were there and the warning only was shown for some
          files, not for all of them.
Cause:    After discussing this issue with @Valloric (see
          https://github.com/Valloric/YouCompleteMe/issues/950), it
          turned out that not YCM, but libclang is responsible for it.
          This is, same compilation flags that produce no warnings with
          clang-the-binary on the command line, do produce them with
          libclang-the-library when used by YCM.
Solution: Add an extra flag (-Wno_newline_eof) to those extracted from
          configuration database before passing them to YCM.
Improve YCM contrib: Improve documentation.
Merge PR #1310 'Improve YCM contrib.'
version: remove "Running in Vi compatible mode" message #1309
Fix sign column redraw

Fixed a bug introduced in SHA:aa66f2487edde49b9a5ba10cd70d706d06a94e25,
due to a misapplied patch. buf_del_sign should redraw the window if the
sign deleted was the last one in the buffer.
Also moved the curwin verification to the correct function.
Merge pull request #1311 from GokuITA/issue1295

Fixed sign column redraw