allowing for 2d contour plots comparing two different set of chains

changes in detail:
- added `-plot-2d` command-line argument to enforce plotting of the triangle plot
- can be used to choose plotting (filled) contours on top of each other,
  or the sencond set of contours is overplotted as contour line
- several changes to analyze.py to enable triangle plots in -comp mode
- output of comparing 2d plots: <chain1>-vs-<chain2>_triangle.pdf
adding likelihood code for the anisotropic CMASS BAO measurement from the BOSS collaboration

changes in detail:
- added gridded likelihood file (in a alpha_perp, alpha_para grid) for this measurment
- added identifiers to data/bao_2013.txt
- added a new Likelihood class `bao_boss_aniso` for this measurment using the likelihood grid
- added a new Likelihood class `bao_boss_aniso_gauss_approx` which approximates the true likelihood by an Gaussian prior
  (NOTE: in contrast to `bao_boss` the correlation between H and Da measurements is taken into account)
- minor whitespace adjustment in bao_known_rs.data
- the `bao_boss` class is changed such that any anisotropic BAO measurement using the CMASS sample prohibits the isotropic CMASS measurment to be taken into account
- including `bao_boss_aniso` and `bao_boss_aniso_gauss_approx` at the same time is prohibited
2d contour plots in comparison mode now without tabulators and the correct number of intendation spaces
Formatting, fixing imports
Merge branch 'comp_2d_contour_plots' of github.com:jngrb/montepython_public into jngrb-comp_2d_contour_plots

* 'comp_2d_contour_plots' of github.com:jngrb/montepython_public:
  2d contour plots in comparison mode now without tabulators and the correct number of intendation spaces
  allowing for 2d contour plots comparing two different set of chains
Trying some transparency modifications
Fixed tab indent
Regexp fixed in reading likelihood params
removed tabs from the file
Implementation of 2d comparison between two folders

See the option in parser_mp. You can now specify the option -plot-2d, when
comparing two runs in two folders, that will allow you to regulate the
behaviour concerning the plotting of the triangle plot when comparing.

* jngrb-comp_2d_contour_plots:
  removed tabs from the file
  Fixed tab indent
  Trying some transparency modifications
  2d contour plots in comparison mode now without tabulators and the correct number of intendation spaces
  allowing for 2d contour plots comparing two different set of chains
first naive implementation of mpi run
improved tests for parralelization / but still Test02 conflicts
update the TODO
Better implementaion of mpi communication, with error passing
Fixed example.param for the current list of experiments
added a clearer error message for clik not finding files
improved clik error messages
First implementation of an MPI rudimentary scheme

* mpi:
  Better implementaion of mpi communication, with error passing
  update the TODO
  first naive implementation of mpi run
added a note on sub-covariance matrix
Merging improved parser

* 'parser' of github.com:montefra/montepython_public:
  README adapted to subparsers
  Tests adapted to use the subparsers
  `argparse.ArgumentParser` subclassed to use `io_mp.ConfigurationError` for unified look of errors
  function `recover_local_path` adapted to subparsers. in function `initialise` indented all code supposed to `run`
  adapted to subparser when calling function `analyze`
  Bug fix: the warning is to be given only if `old_param` is given
  added custom parser types (`positive_int`, `existing_file`). created a `run` and an `info` subparser to distinguish better between the two operation modes. Removed check of `N` (done by custom type). Some cleanup of the parser done
  added descriptive name in `test_configuration_file` doc `test_short_run` changed according to new option name (`--info`)
  README adjusted to the latest options convenstions. Some code enhancement added. A forgotten `code/` directory substituted by `montepython`
  forgot to use the `CHparser`. Now fixed
  Added parser argument groups for MultiNest and CosmoHammer
  Removed non needed `dest`. `argparse` infers them from the long name of the option. Replaced `-` with `--` in options long names, as per convention. Fixed boolean options.

Conflicts:
	montepython/parser_mp.py
	tests/test_montepython.py