move all translation scripts to tools/

I think we should just move all the scripts to tools/, app/tools is
confusing, not very visible, and non-standard.

.gitlab-ci.yml

@@ -12,7 +12,7 @@ before_script:
 
 test:
   script:
-    - ./app/tools/check-string-format.py
+    - ./tools/check-format-strings.py
     - ./gradlew assemble -PdisablePreDex
     # always report on lint errors to the build log
     - sed -i -e 's,textReport .*,textReport true,' app/build.gradle

app/tools/remove-unused-trans.py → tools/remove-unused-and-blank-translations.py

 #!/usr/bin/env python3
 
-# Remove extra translations
+# This script removes strings from the translated files that are not useful:
+#  * translations for strings that are no longer used
+#  * empty translated strings, English is better than no text at all
 
 import glob
 import os
 import re
 from xml.etree import ElementTree
 
+resdir = os.path.join(os.path.dirname(__file__), '..', 'app', 'src', 'main', 'res')
+
 strings = set()
 
-for e in ElementTree.parse(os.path.join('src', 'main', 'res', 'values', 'strings.xml')).getroot().findall('.//string'):
+for e in ElementTree.parse(os.path.join(resdir, 'values', 'strings.xml')).getroot().findall('.//string'):
     name = e.attrib['name']
     strings.add(name)
 
-for d in glob.glob(os.path.join('src', 'main', 'res', 'values-*')):
+for d in glob.glob(os.path.join(resdir, 'values-*')):
 
     str_path = os.path.join(d, 'strings.xml')
     if os.path.exists(str_path):