Merge pull request #1950 from jchodera/fix-references

Eliminate stray non-ASCII characters from references.bib since this breaks sphinx

.travis.yml

@@ -183,6 +183,7 @@ script:
   - if [[ ! -z "${DOCS_DEPLOY}" && "${DOCS_DEPLOY}" = "true" ]]; then
       pip install sphinx==1.5.6 sphinxcontrib-bibtex sphinxcontrib-lunrsearch sphinxcontrib-autodoc_doxygen;
       make sphinxhtml;
+      make sphinxpdf;
       make C++ApiDocs PythonApiDocs;
       mkdir -p api-docs;
       mv sphinx-docs/userguide/html api-docs/userguide;

docs-source/usersguide/references.bib

@@ -41,7 +41,7 @@
 
 @article{Best2012,
    author = {Best, Robert B. and Zhu, Xiao and Shim, Jihyun and Lopes, Pedro E. M. and Mittal, Jeetain and Feig, Michael and MacKerell, Alexander D.},
-   title = {Optimization of the Additive CHARMM All-Atom Protein Force Field Targeting Improved Sampling of the Backbone ϕ, ψ and Side-Chain χ1 and χ2 Dihedral Angles},
+   title = {Optimization of the Additive CHARMM All-Atom Protein Force Field Targeting Improved Sampling of the Backbone $\phi$, $\psi$, and Side-Chain $\chi_1$ and $\chi_2$ Dihedral Angles},
    journal = {Journal of Chemical Theory and Computation},
    volume = {8},
    number = {9},