Prepare for new colout version

Because there is a weird `v0.11` tag, we pick the next version `v0.12.0`,
instead of the "real" next version aka `v0.7.0`

This project is considered to use Semantic Versioning (https://semver.org/)
(https://semver.org/spec/v2.0.0.html as of now)

Python versioning updates:
* Unify that package is offered for >=Python3.5
  2.7 support was dropped in dab5555503,
  and <3.5 versions do not exist in https://devguide.python.org/#status-of-python-branches as of committing time

* Add some classifiers (YMMV, my first pip package)
* Add some bare-bones `tox` configuration (YMMV, my first tox interaction)
* Add packages required for packaging/deployment in `requirements-build.txt`
* `README.md` is not required to be packaged anymore - it is read at install time
  * Fix Content-Type for PyPI

* Update `README.md`:
  * Reorder installation options (`pip` > `pipsi` > `ppa`)
  * Hard wrap at 100 chars for "meaningful" offences.
  * Add myself as maintainer
  * Remove escapes that don't make sense in CommonMark
    (GFM, as project is hosted in Github)
  * Fix typos

* Add a more complete `.gitignore` file

.gitignore

@@ -1,5 +1,162 @@
-*.pyc
+## Python gitignore
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
 build/
+develop-eggs/
 dist/
-colout.egg-info/
+downloads/
+eggs/
 .eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+.hypothesis/
+.pytest_cache/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# pyenv
+.python-version
+
+# celery beat schedule file
+celerybeat-schedule
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+
+## Jetbrains
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio and WebStorm
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff
+.idea/**/workspace.xml
+.idea/**/tasks.xml
+.idea/**/usage.statistics.xml
+.idea/**/dictionaries
+.idea/**/shelf
+
+# Sensitive or high-churn files
+.idea/**/dataSources/
+.idea/**/dataSources.ids
+.idea/**/dataSources.local.xml
+.idea/**/sqlDataSources.xml
+.idea/**/dynamic.xml
+.idea/**/uiDesigner.xml
+.idea/**/dbnavigator.xml
+
+# Gradle
+.idea/**/gradle.xml
+.idea/**/libraries
+
+# Mongo Explorer plugin
+.idea/**/mongoSettings.xml
+
+# Editor-based Rest Client
+.idea/httpRequests
+
+# SonarLint
+.idea/sonarlint
+
+# CMake
+cmake-build-*/
+
+# File-based project format
+*.iws
+
+# IntelliJ
+out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Cursive Clojure plugin
+.idea/replstate.xml
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties