title: Open cir sp sim with spice syntax
body: <p><strong>Problem statement:</strong>
  When I open a file with .sp extention with vim it opens with spice syntax which the same file with .sim/.cir extension does not open with spice syntax.</p>
  <p><strong>My efforts:</strong>
  I tried by added the below line in .vimrc but it's not working.</p>
  <p><code>au BufRead *.sim setfiletype spice</code></p>
  <p><strong>Details:</strong>
  I have the following lines in .vimrc</p>
  <p><code>syntax on</code></p>
  <p><code>filetype on</code></p>
  <p><strong>Looking for:</strong> I am looking for an option that we can add in .vimrc to enable a set of file extensions(sim/cir/sp) to open with a spice syntax.</p>
  <p>Thanks.</p>