Turbulence: Improved plot layout
Merge branch 'master' of github.com:python-acoustics/python-acoustics into turbulence
Octave: several improvements

- Let certain methods call functions instead of duplicating their logic.
Include references to these functions in the docstrings.
- lower_frequency and upper_frequency now also have order=1 by default.
Merge pull request #40 from FRidh/turbulence

Turbulence: Improved plot layout
Integer -> Floats

At many places integers were used while floats should be used. Often
this works fine but not always, resulting in hard to find errors.

Changes:

- Integer -> Float in many places
- SOUNDSPEED module constant
- NC curves are now in a dictionary.
Turbulence: Improved plot layout
Travis
Merge pull request #43 from FRidh/travis

Travis: Use conda
Using pytest in Travis
Merge pull request #45 from felipeacsi/travis-numba-tests

Using pytest in Travis
Merge branch 'master' of github.com:python-acoustics/python-acoustics into octave
Merge pull request #41 from FRidh/octave

Octave: several improvements
Turbulence: Improved plot layout
Travis
Using pytest in Travis
Re-organizing utils
Fix docs
Merge pull request #38 from felipeacsi/esum

Re-organizing utils
Merge branch 'master' of github.com:python-acoustics/python-acoustics into room

Conflicts:
	acoustics/core/descriptors.py
Merge pull request #44 from FRidh/room

Integer -> Floats