Enable bracketed paste

[echasnovski]

Is your feature request related to a problem? Please describe.
When sending multiline statement to interactive REPL environments (such as radian for R and ipython for Python), they get inappropriately indented. This is because sent text is treated as typed manually and those environments already have automatic indentation when typing manually.

To solve this issue, enabling bracketed paste mode seems to be the most universal solution. There has already been several direct attempts (#190, #233, #234) along with indirect ones, which mainly deal with Python (for example, #274).

Describe the solution you'd like
I'll propose a solution in a separate PR. This issue is intended as a placeholder to describe a problem.

Describe alternatives you've considered
There is a g:neoterm_repl_enable_ipython_paste_magic setting, which uses ipython specific solution for enabling pasting. This doesn't work for any other REPL environments.