Pywebexec

* batch / parallel jobs using `/command/<command>` schema:
* run-para python module integration
* schema_options:
* batch_param: `<param>`
* transform `<param>` to textarea to launch multiple commands with each value replacing `batch_param`
* add range params for `/command/<command>`:
* parallel: nb parallel jobs to execute
* delay: initial delay in s for jobs execution

* use input placeholders/values to define initial width

* fix for Safari input number / max-width

* add run-para option (to use with run-para python module)
* input number width calculation / dynamic width

* textarea border bottom right for resize

* form textarea border-radius