title: Finding supported GLSL version
body: <p>How would one best do to find the version of GLSL that an OpenGL implementation supports, in a way that can be reliably used programmatically?</p>
  
  <p>Is the best way to get the <code>GL_SHADING_LANGUAGE_VERSION</code> string and try to parse it? Can it be relied upon to be returned in a well-defined format? My Intel driver returns <code>1.20</code> which is simple enough to parse, but my nVidia card returns <code>4.20 NVIDIA via Cg compiler</code>. Can it be trusted to be matched by the <code>(\d+)\.(\d+)( .*)?</code> regex? <a href="https://stackoverflow.com/questions/3456669/what-version-of-glsl-is-used-in-the-iphones/10018155#10018155">This answer</a> seems to indicate otherwise, returning <code>OpenGL ES GLSL ES 1.0</code>.</p>
  
  <p>Is any of this correct, and/or is there some other way? Specifically, I want to check so that at least GLSL 1.20 is supported.</p>