Fix gallery location generation

This creates two separate directories in the 'gallery' subdirectory so
that they don't overlap.  Previously, a host of warnings and potentially
incorrect behaviour happened because the build directory was inside the
source directory.

Author: jakelishman

doc/.gitignore

@@ -8,4 +8,4 @@
 
 _build
 _images
-gallery/qutip_examples
+gallery/build

doc/conf.py

@@ -294,8 +294,8 @@
 # Sphinx Gallery
 
 sphinx_gallery_conf = {
-     'examples_dirs': 'gallery',   # path to your example scripts
-     'gallery_dirs': 'gallery/qutip_examples',  # save generated examples
+     'examples_dirs': 'gallery/src',   # path to your example scripts
+     'gallery_dirs': 'gallery/build',  # save generated examples
      'abort_on_example_error': True  # abort if exception occurs
 }
 

doc/gallery/README.rst renamed to doc/gallery/src/README.rst

@@ -15,7 +15,7 @@ QuTiP: Quantum Toolbox in Python
    frontmatter.rst
    installation.rst
    guide/guide.rst
-   gallery/qutip_examples/index.rst
+   gallery/build/index.rst
    apidoc/apidoc.rst
 
    :maxdepth: 1