Fix error line numbers when a range is run
Stopping if debugger found
Make virtualenv.vim compatible with Python 3.

The `virtualenv.vim` file used the `execfile()` function to run the
`activate_this.py` script from the active virtual environment. However,
`execfile()` was removed in Python 3. This replaces the call to
`execfile()` with a process that should be compatible with Python 2 and
Python 3:

1. Read the script contents into a string.
2. Pass the string to `compile()` to get a compiled script object.
3. Pass the compiled script object to `exec()`.
Add a set of `g:pymode_lint_*_symbol` options.

[Inspired by
Syntastic](https://github.com/scrooloose/syntastic/blob/master/plugin/syntastic/signs.vim#L10-L24),
this feature allows users to set, in their `~/.vimrc` file, a custom set of error symbols.
Merge pull request #295 from kdeldycke/develop

Add a set of g:pymode_lint_*_symbol options.
Update changelog.
Merge pull request #293 from mlmoses/fix-virtualenv-execfile

Make virtualenv.vim compatible with Python 3.
Merge pull request #289 from ethanvandenberg22/develop

Stopping if debugger found
Merge pull request #286 from lawrenceakka/line-number-fix

Fix error line numbers when a range is run
Merge branch 'develop' of github.com:klen/python-mode into develop
Updated README.rst
Fix dockstring in default_config due to H402 rule

When we run pep8 tests in a root project folder, flake8 with default
settings also checks .ropeproject/ folder and finds two errors there.

pep8 runtests: commands[0] | flake8
./.ropeproject/config.py:5:1: H402  one line docstring needs punctuation.
./.ropeproject/config.py:84:1: H402  one line docstring needs punctuation.

So I fixed these dockstrings to avoid such confusion
Update pylama
Update Makefile
Merge pull request #304 from vikt0rs/fix-docstring-punctuation

Fix dockstring in default_config due to H402 rule
Merge pull request #302 from westurner/update_readme

Updated README.rst
Merge branch 'develop' of github.com:klen/python-mode into develop
Fix modeline
Update version
Merge branch 'release/0.6.19'