Customizable update of toolbar buttons (i.e. 'methods') according to PLCStatus

Fixed small typo in error message.

WAMP : complains about failure to start WAMP only if it was successfully imported.

WAMP: now config and secret given in project files always override those given in commandline. Also made extensions web customisations happen before registration of web interface.

Moved Wamp configuration file selection logic into runtime/wampclient.py. Added Wamp CRA secret file upload and download. Slightly reworked code for config and secret file loading and saving.

Added a way for extension to register dedicated URL under settings page URL (i.e. /settings/something)

Fixed a bit of everything in WAMP, and added web settings for that same extension.

Added some immutable field (platform) in default runtime web setting page, for the example.

Fix misc typos in exception handling code.

Fixed i18n related typo.

Fixed typo

Better logging of Nevow Server import in case of exception.

WampClient : Simplified, removed dead code, use exception for handling failures and misconfiguration, check existence of mandatory parameters.

Merged #2486, enhancements to WAMP client : auto reconnecting, wamp conf checking and saving, additional attributes for exposed calls, etc

Nevow based web interface now show simple Log message sending form for basic runtime, and allow extensions to add their own web settings.

Now, runtime extensions should be able to add their own settings to web configuration interface.