Avoid printing an error response when detecting xclip.

While we're at, using the slightly more portable `command -v` technique
to detect the executable.  Also, there's no need to use `io.popen()` if
we aren't going to record the path.  Instead, let's use the simpler
`os.execute()` to detect the presence of xclip.
Merge pull request #1555 from jszakmeister/silent-xclip-find-executable

Avoid printing an error response when detecting xclip.
Add Boolean argument escape_csi to vim_feedkeys

- By default vim_feedkeys escaped all input for CSI/K_SPECIAL bytes
  before using it. However since vim_replace_termcodes() also escapes
  the input string chaining these functions together escapes input twice
- vim_feedkeys() now takes a third Boolean argument to enable/disable
  escaping
- Breaks API compatibility
Functional tests for feedkeys CSI escaping

- tests for vim_feedkeys and replace_termcodes
Merge PR #1270 'Add Boolean argument escape_csi to vim_feedkeys'
Change refs for joyent/libuv repo to libuv/libuv

* References to old repository found through grepping
* Replace references from github.com/joyent/libuv to github.com/libuv/libuv
* Fix previous commit by not including whitespace changes

 For issue #1560.
ui: Remove ui_inchar/ui_char_avail

Also:

- Remove NO_CONSOLE_INPUT/NO_CONSULE preprocessor conditionals
- Remove ctrl_c_interrupts variable, check for mapped_ctrl_c directly in
  process_interrupts()
- Move ui_inchar profiling to input_poll which is where Nvim blocks for input.
ui: Remove ui_delay, ui_breakcheck and ui_set_shellsize

These functions only used to call another os_* function, so remove them and
replace all occurences in the project.
ui: Extract mouse.c/mouse.h
ui: Remove redundant ui.h includes

Also move read_error_exit to os/input.c
Merge PR #1565 'Cleanup ui module'
Merge pull request #1562 from Happy-Dude/fix-1560-libuv-refs

Change refs for joyent/libuv repo to libuv/libuv.
Wconversion: Fix warnings in ex_eval.c.
Wconversion: Fix warnings in file_search.c.
Wconversion: Fix warnings in indent_c.c.
Wconversion: Remove regexp_nfa.c from list.
Wconversion: Change long to int64_t in cursor_shape.c, digraph.c.

Warnings were fixed in #1488.
eval: Fix coverity false positive.

** CID 74786:  Resource leak  (RESOURCE_LEAK)
/src/nvim/eval.c: 10614 in f_jobsend()
/src/nvim/eval.c: 10616 in f_jobsend()

save_tv_as_string() should return NULL and input_len <= 0 for an empty
string or error. Callers should check that input != NULL instead of
input_len > 0 and assert(input == NULL) when the length must be checked.
vim-patch:7.4.425: Adjust virtcol when showbreak is set

vim-patch:7.4.425

Problem:    When 'showbreak' is used "gj" may move to the wrong
position. (Nazri Ramliy)
Solution:   Adjust virtcol when 'showbreak' is set. (Christian Brabandt)

https://code.google.com/p/vim/source/detail?r=v7-4-425
vim-patch:7.4.435: Disable linebreak temporarily when formatting lines.

vim-patch:7.4.435

Problem:    Line formatting behaves differently when 'linebreak' is set.
            (mvxxc)
Solution:   Disable 'linebreak' temporarily. (Christian Brabandt)

https://code.google.com/p/vim/source/detail?r=v7-4-435