Add a Runtime Thread helper to check if a thread is in a state where it
will not change at least until next frame. This includes any state
where the thread is done, as that will not change either.
The new `maybeFormatMessage` function detects whether its argument
looks like a message descriptor object and, if so, will call
`formatMessage` on it. This is now used for all user-visible text fields
in extensions.
Also, messages may use "select" to check the target type with a message
like this: '{targetType, select, stage {text for stage} sprite {text for
sprite} other {text for other}'. Note that the "other" clause is
required by `formatMessage`.
A LOOP block is like a conditional, but the LOOP block will be
re-evaluated after any child branch runs.
Also:
- Support using '---' as a block separator
- Refactor common code from `_registerExtensionPrimitives` and
`_refreshExtensionPrimitives` into new `_fillExtensionCategory`
- Improve error reporting during block conversion
Towards fixing #865. This adds an IO class for detecting the mouse wheel
being scrolled. Basic tests are included; they mock the runtime to see
what blocks are activated by scrolling.
Store the thread's blocks at blockContainer letting execute quickly
determine the block source. Monitor threads are a monitor thread. They
do not become a target thread suddenly.
* localize the block and menu strings in the pen extension
* adds .tx/config to be able to push translations to transifex
* includes format-message to localize strings and extracting them.
* add setLocale function to VM to allow GUI to pass in locale data.
* refresh block definitions when the locale changes.
### Still to be decided
For now just extracting messages from the pen extension into their own file. We’ll need to decide if each category gets its own file, or group all the strings into one resource.
Before: `_removeThread` stops a thread and immediately removes it from
the runtime's thread array. If this happens while iterating over the
thread array, such as in the case of clone deletion, some elements of
the array can be missed.
After: `_removeThread` has been renamed to `_stopThread`. It still stops
the thread immediately but it no longer removes the thread from the
runtime's thread array. Instead, `_stopThread` marks the thread for
later removal. Such threads are removed at the top of the next `_step`.
