Add timer feature for code reading

[hvaldecantos]

When a participant starts a new experimental system, he/she has a limited amount of time to read its code. The time constraint should be only on the code reading, not on task (questions) reading.

• The timer should appear on the right hand in the status bar, and it only decreases its time when the code is shown (code viewer window). Then, the timer needs methods for starting, stopping.
• The timer should appear only in the system, tasks, and code viewer windows.
• The remaining time should be saved in the participant’s session db document, so, when the participant retakes the reading of the same experimental system the timer resumes from where it was left.
• The time limit should be set in the config.yml file.

[hvaldecantos]

This is related to issue #15 and it is being developed in branch qstatusbar in pull request #16

[hvaldecantos]

• a new system resets the timer
• set the time for the timer from the config file
• save in the db the remaining time??

[hvaldecantos]

Does saving the timer time in the db would affect the eye tracker samples we can take while the participant is reading the code?