Standardize package names: lower-case, not Mixed_CASE (#2475)

* Rename packages

* Upcasing depends_on() in packages.

* Downcased extends('r')

* Fixed erroneously changed URL that had slipped through.

* Fixed typo

* Fixed link from documentation into package source code.

* Fixed another doc problem.

* Changed underscores to dashes in package names.

* Added test to enforce lowercase, no-underscore naming convention.

* Fix r-xgboost

* Downcase more instances of 'R' in package auto-creation.

* Fix test.

* Converted unit test packages to use dashes not underscores

* Downcase `r` in the docs.

* Update module_file_support.rst

Fix r->R for class R.

var/spack/repos/builtin/packages/octave/package.py

@@ -85,7 +85,7 @@ class Octave(Package):
     depends_on('glpk',         when='+glpk')
     depends_on('gl2ps',        when='+gl2ps')
     depends_on('gnuplot',      when='+gnuplot')
-    depends_on('ImageMagick',  when='+magick')
+    depends_on('image-magick',  when='+magick')
     depends_on('hdf5',         when='+hdf5')
     depends_on('jdk',          when='+jdk')
     depends_on('llvm',         when='+llvm')
@@ -162,7 +162,7 @@ def install(self, spec, prefix):
 
         if '+magick' in spec:
             config_args.append("--with-magick=%s"
-                               % spec['ImageMagick'].prefix.lib)
+                               % spec['image-magick'].prefix.lib)
 
         if '+hdf5' in spec:
             config_args.extend([