Add a makefile defining some common tasks.

This makefile makes it easier to run things like unit tests and pylint
against the code. Especially before doing a commit. It also helps ensure
unit tests are not affected by local config files (e.g., ~/.xonshrc).

Makefile

@@ -0,0 +1,47 @@
+SHELL = /bin/sh
+
+all:
+	@echo "You must specifiy a make target."
+	@echo "Targets are:"
+	@echo "  clean"
+	@echo "  lint"
+	@echo "  lint-all"
+	@echo "  test"
+	@echo "  test-all"
+	@echo "  build-tables"
+
+clean:
+	rm -f xonsh/lexer_table.py xonsh/parser_table.py
+	rm -f xonsh/lexer_test_table.py xonsh/parser_test_table.py
+	rm -f xonsh/*.pyc tests/*.pyc
+	rm -f xonsh/*.rej tests/*.rej
+	rm -fr build
+
+# Line just the changed python files. It doesn't matter if "git add" has
+# already been done but obviously if you've already done "git commit" then
+# they're no longer consider changed. This should be run (along with "make
+# test") before commiting a set of changes.
+lint:
+	pylint $$(git status -s | awk '/\.py$$/ { print $$2 }' | sort)
+
+# Lint all the python files.
+lint-all:
+	make clean
+	pylint $$(find tests xonsh -name \*.py | sort)
+
+# Test just the changed python files. It doesn't matter if "git add" has
+# already been done but obviously if you've already done "git commit" then
+# they're no longer consider changed. This should be run (along with "make
+# lint") before commiting a set of changes.
+test:
+	scripts/run_tests.sh -e
+
+# Test all the python files.
+test-all:
+	scripts/run_tests.sh
+
+# Build the parser_table.py module. This is normally done by setup.py at
+# install time. This just makes it easy to create the parser module on the fly
+# to facilitate development.
+build-tables:
+	python3 -c 'import setup; setup.build_tables()'

scripts/run_tests.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+#
+# Run all the nosetests or just the ones relevant for the edited files.
+#
+if [[ $1 == "-e" ]]; then
+    tmp_file=$(mktemp /tmp/nose_tests_XXXXXX)
+    git status -s |
+        awk '/\.py$/ { print $2 }' |
+        while read f; do
+            if [[ $f == xonsh/* ]]; then
+                f="tests/test_$(basename  $f)"
+                if [[ -f $f ]]; then
+                    echo $f
+                fi
+            else
+                echo $f
+            fi
+        done |
+        sort -u > $tmp_file
+    XONSHRC=/dev/null nosetests -v $(< $tmp_file)
+    rm $tmp_file
+else
+    XONSHRC=/dev/null nosetests
+fi