scripts: introduce import cleanup using isort

dev_requirements.txt

@@ -1,8 +1,9 b''
 pytest >= 3.3.0, < 4.7
 pytest-runner < 5.2
 pytest-sugar >= 0.7.0, < 0.10
 pytest-benchmark < 3.3
 pytest-localserver < 0.6
 mock < 3.1
 Sphinx < 1.9
 WebTest < 2.1
+isort == 4.3.21

scripts/whitespacecleanup.sh

@@ -1,20 +1,23 b''
 #!/bin/bash -x
 
 # Enforce some consistency in whitespace - just to avoid spurious whitespaces changes
 
 files=`hg mani | egrep -v '/fontello/|/email_templates/|(/lockfiles.py|^LICENSE-MERGELY.html|^docs/Makefile|^scripts/whitespacecleanup.sh|/(graph|mergely|native.history)\.js|/test_dump_html_mails.ref.html|\.png|\.gif|\.ico|\.pot|\.po|\.mo|\.tar\.gz|\.diff)$'`
 
 sed -i "s/`printf '\r'`//g" $files
 sed -i -e "s,`printf '\t'`,    ,g" $files
 sed -i -e "s,  *$,,g" $files
 sed -i -e 's,\([^ ]\)\\$,\1 \\,g' -e 's,\(["'"'"']["'"'"']["'"'"']\) \\$,\1\\,g' $files
 # ensure one trailing newline - remove empty last line and make last line include trailing newline:
 sed -i -e '$,${/^$/d}' -e '$a\' $files
 
 sed -i -e 's,\([^ /]\){,\1 {,g' `hg loc '*.css'`
 sed -i -e 's|^\([^ /].*,\)\([^ ]\)|\1 \2|g' `hg loc '*.css'`
 
 hg mani | xargs chmod -x
 hg loc 'set:!binary()&grep("^#!")&!(**_tmpl.py)&!(**/template**)' | xargs chmod +x
 
+# isort is installed from dev_requirements.txt
+isort --line-width 160 --wrap-length 160 --lines-after-imports 2 `hg loc '*.py'`
+
 hg diff