Add live validation of the hint chars setting

- onchange: to lowercase and remove duplicate chars

- Update pref defaults in locales
Fix: commit 586dd356 broke hint marker rotation
Merge pull request #185 from lydell/develop

Fix: commit 586dd356 broke hint marker rotation
missing options entry for Polish locale
Closes #143. Readonly inputs can now be followed using hint markers
Merge pull request #177 from lydell/better-options

Better options
Merge remote-tracking branch 'source/develop' into mine