[WIP]vim-patch:7.4.276

updated for version 7.4.276
Problem:    The fish shell is not supported.
Solution:   Use begin/end instead of () for fish. (Andy Russell)

https://code.google.com/p/vim/source/detail?r=a6b59ee633a355095e6473ec5e2a7d9088bfb853

Notes:
1. I removed a line from the comment above get_isolated_shell_name that referenced different behavior in Windows, since that ifdef has been removed.
2. I added line 2377 to option.c, because it seems like it must have been deleted by mistake. It's present in vim, but Neovim just has the bracketed section of code without the if statement.