Split column in multiple rows

[pect]

Hello,

I'd be very grateful if you could help me with an issue I've been struggling all the day through.

I have data in below format (1st image) where some columns have multiple values separated by commas. 

Instead, I need to split columns "task", "start date", "finish date" and "checkpoint" into as many rows as different data are in each cell. Note that each cell has the same number of items for each id (i.e. id A has 3 tasks, 3 start and finish dates, and  3 checkpoints whereas id B has 4 of each). So, the table I am trying to model is the following:

Thank you very much in advance.

Àlex