Revive pep8 linting and grep for tab characters.

There are still a bunch of errors.  Not all of them need to be fixed.

build/actions.sh

@@ -177,9 +177,9 @@ clean-pyc() {
# NOTE: Not deleting cpython-full.  Maybe we should, or we should put it in a
# diffent directory?
clean() {
	rm -r -f _build _release
	rm -f _bin/oil.* _bin/hello.*
	clean-pyc
  rm -r -f _build _release
  rm -f _bin/oil.* _bin/hello.*
  clean-pyc
}

"$@"

test/lint.sh

@@ -53,21 +53,36 @@ format-demo() {

# yapf: was useful, but might cause big diffs

# After 'pip install pep8' on Ubunu, it's in ~/.local.
bin-pep8() {
  ~/.local/bin/pep8 "$@"
}

# disable:
# E226: missing whitespace around arithmetic -- I want to do i+1
# E302: expected two blank lines, found 1 (sometimes one is useful).
# E265: Although I agree with this style, some comments don't start with '# '
# E111,E114: we use 2 space indents, not 4
oil-pep8() {
  local temp=E501  # line too long
  pep8 --ignore E125,E701,E241,E121,E111,E128,E262,E226,E302,$temp "$@"
  # These could be enabled.
  local temp=W291,E501,E303  # trailing whitespace, line too long, blank lines
  bin-pep8 --ignore E125,E701,E241,E121,E111,E114,E128,E262,E226,E302,E265,$temp "$@"
}

pep8-all() {
  oil-pep8 {asdl,bin,core,osh,oil,opy}/*.py "$@"
  oil-pep8 {asdl,bin,core,osh}/*.py "$@"
}

# Language independent
find-tabs() {
  find . '(' -name _tmp -o -name $PY27 ')' -a -prune -o \
  # benchmarks/testdata should be excluded
  find . '(' -name _tmp \
          -o -name _chroot \
          -o -name _deps \
          -o -name testdata \
          -o -name $PY27 \
         ')' \
         -a -prune -o \
         '(' -name '*.py' -o -name '*.sh' ')' -a -print |
    xargs grep -n $'\t'
}