* [BridgeAbstract] Implement customizable cache timeout
The customizable cache timeout is used instead of the default cache
timeout (CACHE_TIMEOUT) if specified by the caller.
* [index] Add new global parameter '_cache_timeout'
The _cache_timeout parameter is an optional parameter that can be
used to specify a custom cache timeout. This option is enabled by
default.
It can be disabled using the named constant 'CUSTOM_CACHE_TIMEOUT'
which supports two states:
> true: Enabled (default)
> false: Disabled
* [BridgeAbstract] Change scope of 'getCacheTimeout' to public
* [html] Add cache timeout parameter to all bridges
The timeout parameter only shows if CUSTOM_CACHE_TIMEOUT has been set
to true. The default value is automatically set to the value specified
in the bridge.
* [index] Disable custom cache timeout by default
8ba817478b