add support for vim Terminal

[OnStarPrograms]

the below commands would add support for people who have vim terminal enabled, allowing for faster editing, and enjoy their terminal in their installed theme, speeding up development in machines that take longer to boot vim such as in a virtual machine.

if has('terminal') == 1                                                                                     
 map <Leader>t :term ++close<cr>                                                                             
 tmap <Leader>t <c-w>:term ++close<cr>                                                                       
                                                                                                             
 map <Leader>T :tab term ++close<cr>                                                                         
 tmap <Leader>T <c-w>:tab term ++close<cr>                                                                   
endif

If you would want, I can create a pull request