Simplify init.vim and move settings to autoload and after directory

after/ftplugin/cpp.vim

@@ -0,0 +1 @@
+nnoremap <F9> :w <CR> :!g++ -Wall -std=c++11 % -o %<&&./%<<CR>

after/ftplugin/python.vim

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+" Automatically save current file and execute it when pressing the <F9> key
+" it is useful for small script
+nnoremap <buffer> <F9> :execute 'w !python' shellescape(@%, 1)<CR>

after/ftplugin/tex.vim

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+" Only use the following character pairs for tex file
+if &runtimepath =~? 'auto-pairs'
+	let b:AutoPairs = AutoPairsDefine({'<' : '>'})
+	let b:AutoPairs = {'(':')', '[':']', '{':'}', '<':'>'}
+endif
+set textwidth=79

after/ftplugin/vim.vim

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+" Disable inserting comment leader after hitting o or O
+set formatoptions-=o
+
+" Disable inserting comment leader after hitting <Enter> in insert mode
+set formatoptions-=r
+
+" Set the folding related options for vim script. Setting folding option
+" in modeline is annoying in that the modeline get executed each time the
+" window focus is lost (see http://tinyurl.com/yyqyyhnc)
+set foldmethod=expr foldlevel=0 foldlevelstart=-1
+	\ foldexpr=utils#VimFolds(v:lnum) foldtext=utils#MyFoldText()
+
+" Use :help command for keyword when pressing `K` in vim file,
+" see `:h K` and https://bre.is/wC3Ih-26u
+set keywordprg=:help
+
+" Only define following variable if Auto-pairs plugin is used
+if &runtimepath =~? 'auto-pairs'
+	let b:AutoPairs = AutoPairsDefine({'<' : '>'})
+
+	" Do not use `"` for vim script since `"` is also used for comment
+	let b:AutoPairs = {'(':')', '[':']', '{':'}', "'":"'", "`":"`", '<':'>'}
+endif