Expand transition probability variables

[vincentvanhees]

Ian Meneghel Danilevicz proposed via e-mail some expansions to the g.fragmentation function, which I am now reviewing and will integrate in GGIR. For example, transition probably for sleep to wake and wake to sleep.

Currently g.fragmentation is applied to only the waking hours of the day. Needed,

• Update g.fragmentation to take into account when the focus is on waking hours (current use case) or SPT (to be developed). In the SPT use case we would probably skip some of the fragmentation metrics and focus only on wake/sleep classification.
• Expand unit tests to cover new scenario
• Update g.part5 to apply g.fragmentation twice, once to waking hours and once to SPT window.
• Test in cohort
• Ask Ian Danilevicz to help check and help revise vignette documentation.

[vincentvanhees]

Closing because this is part of #955