Python3 version of TARDIS (#879)

* add tardis_env3

* clean up tardis 3 env file

* change of setup.py

* update astropy_helpers to 3.1 and make base.py python3 compatible

* upgrade all setup_package to use new astropy_helpers

* update to new version

* make the ctests python3 compatible

* fix the readers from file(xx) to open()
fix the conftest to use the right .so file
rewrite the continuum_compare

* skip problems in test_cmontecarlo

* fixed all python3 pytest errors

* change travis to python 3

* adding language directive

* Fix continuum_compare_data to be compatible with python3

* Remove duplicate import of cmontecarlo_methods

* Fix xfail in test_bf_cross_section

* moved density comment to properties from parameters (#25)

* moved density comment to properties from parameters

* moved all @Property comments to property section from parameter docstring

* added luminosity_requested and electron_densities to model class docstring

* convert @Property comments to numpydoc style Attribute comments.

* use Astropy 1.3 constants throughout TARDIS

* convert byte strings in atomic hdf5 to actual strings with ascii
encoding

* add the use of tardis constants to all files in tardis

* python3 fix

* fix pep8 and deprecatio

* fix python3

* fix for unit constants

* update pandas to use loc

* fix the .dot reference file and update the dot2tex installation

* update travis to work with the new tardis3 refdata

* update tests for plasma dot

* fix python3 print

* remove dot2tex testing as it is not python 3 compatible yet

* fix python 3 print statements again

* use new ah_bootstrap.py

.travis.yml

@@ -19,7 +19,6 @@ sudo: true
 env:
     global:
         - COMPILER=gcc
-        - PANDAS_VERSION=0.16
         - ASTROPY_USE_SYSTEM_PYTEST=1
         - SETUP_CMD='test'
         - TEST_MODE='normal'
@@ -49,8 +48,9 @@ before_install:
     - if [[ $TEST_MODE == 'spectrum' ]]; then git fetch origin; fi
     - if [[ $TEST_MODE == 'spectrum' ]]; then git checkout origin/master; fi
     # Use the following to get the ref-data from a specific pull request; 
-    # - if [[ $TEST_MODE == 'spectrum' ]]; then git fetch origin pull/14/head:update-ref; fi
-    # - if [[ $TEST_MODE == 'spectrum' ]]; then git checkout update-ref; fi
+    - if [[ $TEST_MODE == 'spectrum' ]]; then git fetch origin pull/17/head:update-ref; fi
+    - if [[ $TEST_MODE == 'spectrum' ]]; then git checkout update-ref; fi
+
     - if [[ $TEST_MODE == 'spectrum' ]]; then git lfs pull --include="atom_data/kurucz_cd23_chianti_H_He.h5" origin; fi
     - if [[ $TEST_MODE == 'spectrum' ]]; then git lfs pull --include="atom_data/chianti_He.h5" origin; fi
     - if [[ $TEST_MODE == 'spectrum' ]]; then git lfs pull --include="unit_test_data.h5" origin; fi