Clean up installation procedure with pip (#4)

* Move dependencies list from 'requirements.txt' to 'setup.py'.

* Move library version to separate file.

NOTE: gelato now provides version to user:

In [1]: import gelato; gelato.__version__
Out[1]: '0.9.3'

* Enable tests with Python-3.7.

* Update __version__

.travis.yml

@@ -6,17 +6,20 @@ python:
   - "3.5"
   - "3.6"
 
+# Enable 3.7 without globally enabling 'dist: xenial' for other build jobs
+matrix:
+  include:
+    - python: 3.7
+      dist: xenial
+
 # Cache directory $HOME/.cache/pip
 cache: pip
 
 # command before installation: install all dependencies and run CMAKE config
 before_install:
   - python -m pip install --upgrade pip
-  - python -m pip install -r requirements.txt
   - python -m pip uninstall -y sympde
-  - wget https://raw.githubusercontent.com/pyccel/sympde/master/requirements.txt -O requirements_sympde.txt
-  - python -m pip install -r requirements_sympde.txt
-  - python -m pip install git+https://github.com/pyccel/sympde@master
+  - python -m pip uninstall -y gelato
 
 # command to install project
 install:

gelato/__init__.py

@@ -1,4 +1,5 @@
 # -*- coding: UTF-8 -*-
+from .version  import __version__
 from .expr     import *
 from .glt      import *
 from .printing import *

gelato/version.py

@@ -0,0 +1 @@
+__version__ = '0.9.4'

setup.py

@@ -1,11 +1,17 @@
 # -*- coding: UTF-8 -*-
 #! /usr/bin/python
 
-import sys
+from pathlib import Path
 from setuptools import setup, find_packages
 
+# ...
+# Read library version into '__version__' variable
+path = Path(__file__).parent / 'gelato' / 'version.py'
+exec(path.read_text())
+# ...
+
 NAME    = 'gelato'
-VERSION = '0.9.3'
+VERSION = __version__
 AUTHOR  = 'Ahmed Ratnani'
 EMAIL   = 'ahmed.ratnani@ipp.mpg.de'
 URL     = 'https://github.com/ratnania/GeLaTo'
@@ -26,17 +32,28 @@
 #    download_url     = URL+'/tarball/master',
 )
 
+install_requires = [
+
+    # Third-party libraries from PyPi
+    'sympy>=1.2',
+    'numpy>=1.13',
+    'scipy>=0.18',
+    'matplotlib',
+
+    # Our libraries from PyPi
+    'sympde',
+]
+
 # ...
 packages = find_packages(exclude=["*.tests", "*.tests.*", "tests.*", "tests"])
 # ...
 
 def setup_package():
-    if 'setuptools' in sys.modules:
-        setup_args['install_requires'] = ['numpy']
 
-    setup(packages = packages, \
-          include_package_data = True, \
-          zip_safe=True, \
+    setup(packages = packages,
+          include_package_data = True,
+          install_requires = install_requires,
+          zip_safe = True,
           **setup_args)