Close mainwindow on exit
Close mainwindow on exit

- Just like the shell widget, the mainwindow should close on exit

equalsraf/neovim-qt,equalsraf/neovim-qt,0x90sled/neovim-qt,ngkaho1234/neovim-qt,Pireax/neovim-qt,equalsraf/neovim-qt,ngkaho1234/neovim-qt,Pireax/neovim-qt,ravloony/neovim-qt,ravloony/neovim-qt,equalsraf/neovim-qt,ravloony/neovim-qt,Pireax/neovim-qt,0x90sled/neovim-qt,ngkaho1234/neovim-qt,0x90sled/neovim-qt