Fix how wrap setting is applied and restored

Line wrapping wasn't working because the variable was set incorrectly.

Line wrapping was restored without autocmds disabled because the variable was never set. It wasn't restored with autocmd because the variable existence was incorrectly checked.

These changes fix those two bugs. I did a bunch of testing and it all seems to work correctly. I also updated the documentation for g:golden_ratio_wrap_ignored because the "off by default" wording makes it sound like you can make it not modify the wrap setting, which is not currently possible.