Removed syntastic and replaced it with ale

Read more here:
https://github.com/w0rp/ale

sources_non_forked/ale/ale_linters/r/lintr.vim

@@ -0,0 +1,35 @@
+" Author: Michel Lang <michellang@gmail.com>, w0rp <devw0rp@gmail.com>,
+"         Fenner Macrae <fmacrae.dev@gmail.com>
+" Description: This file adds support for checking R code with lintr.
+
+let g:ale_r_lintr_options = get(g:, 'ale_r_lintr_options', 'with_defaults()')
+" A reasonable alternative default:
+"   get(g:, 'ale_r_lintr_options', 'with_defaults(object_usage_linter = NULL)')
+
+
+let g:ale_r_lintr_lint_package = get(g:, 'ale_r_lintr_lint_package', 0)
+
+function! ale_linters#r#lintr#GetCommand(buffer) abort
+    if ale#Var(a:buffer, 'r_lintr_lint_package')
+        let l:lint_cmd = 'lint_package(cache = FALSE, linters = '
+        \   . ale#Var(a:buffer, 'r_lintr_options') . ')'
+    else
+        let l:lint_cmd = 'lint(cache = FALSE, commandArgs(TRUE), '
+        \   . ale#Var(a:buffer, 'r_lintr_options') . ')'
+    endif
+
+    let l:cmd_string = 'suppressPackageStartupMessages(library(lintr));'
+    \   . l:lint_cmd
+
+    return ale#path#BufferCdString(a:buffer)
+    \   . 'Rscript -e '
+    \   . ale#Escape(l:cmd_string) . ' %t'
+endfunction
+
+call ale#linter#Define('r', {
+\   'name': 'lintr',
+\   'executable': 'Rscript',
+\   'command_callback': 'ale_linters#r#lintr#GetCommand',
+\   'callback': 'ale#handlers#gcc#HandleGCCFormat',
+\   'output_stream': 'both',
+\})