codecov: Default 85% coverage target

Also switch to branch, rather than line, coverage.

.codecov.yml

@@ -1,2 +1,8 @@
 comment:
   layout: "header, diff, changes"
+
+coverage:
+  status:
+    project:
+      default:
+        target: 85

.coveragerc

@@ -0,0 +1,19 @@
+[run]
+branch = True
+
+[report]
+# Regexes for lines to exclude from consideration
+exclude_lines =
+    # Have to re-enable the standard pragma
+    pragma: no cover
+
+    # Don't complain about missing debug-only code:
+    def __repr__
+
+    # Don't complain if tests don't hit defensive assertion code:
+    raise AssertionError
+    raise NotImplementedError
+
+    # Don't complain if non-runnable code isn't run:
+    if 0:
+    if __name__ == .__main__.:

.travis.yml

@@ -37,6 +37,7 @@ env:
     - FIREDRAKE_TRAVIS_TESTS=1
     - PACKAGE_MANAGER="--no-package-manager"
     - SLEPC="--slepc"
+    - COVERAGE_DIRS="--cov firedrake"
   matrix:
     - PYOP2_BACKEND=none
 matrix:
@@ -87,7 +88,7 @@ install:
 script:
   - cd firedrake/src
   - (cd firedrake; make lint)
-  - (cd firedrake; rc=0; for t in ${PYOP2_TESTS}; do py.test --cov-append --cov firedrake --short -v tests/${t} || rc=$?; done; exit $rc)
+  - (cd firedrake; rc=0; for t in ${PYOP2_TESTS}; do py.test --cov-append ${COVERAGE_DIRS} --short -v tests/${t} || rc=$?; done; exit $rc)
   - if [ "x$TEST_ADJOINT" != "x" ]; then python dolfin-adjoint/tests_firedrake/test.py; fi
 after_success:
   - (cd firedrake; bash <(curl -s https://codecov.io/bash))