hydrogen-web/doc/FRAGMENTS.md

 - DONE: write FragmentIndex
 - DONE: adapt SortKey ... naming! :
    - FragmentIdIndex (index as in db index)
        - compare(idA, idB)
    - SortKey
        - FragmentId
        - EventIndex
 - write fragmentStore
 - adapt timelineStore
 - adapt persister
    - persist fragments in /sync
    - load n items before and after key
    - fill gaps / fragment filling
 - add live fragment id optimization if we haven't done so already
 - lets try to not have to have the fragmentindex in memory if the timeline isn't loaded
add todo for fragments 2019-04-18 23:50:23 +05:30			`- DONE: write FragmentIndex`
better naming FragmentIndex -> FragmentIdIndex (index of fragment ids, not an index number in a fragment collection) EventKey -> EventIndex (implies being ordered) FragmentKey -> FragmentId (implies not being ordered, hence FragmentIdIndex) 2019-05-01 19:06:32 +05:30			`- DONE: adapt SortKey ... naming! :`
			`- FragmentIdIndex (index as in db index)`
			`- compare(idA, idB)`
adjust SortKey to have fragmentKey instead of gapKey with FragmentIndex to compare fragment keys 2019-05-01 18:17:39 +05:30			`- SortKey`
better naming FragmentIndex -> FragmentIdIndex (index of fragment ids, not an index number in a fragment collection) EventKey -> EventIndex (implies being ordered) FragmentKey -> FragmentId (implies not being ordered, hence FragmentIdIndex) 2019-05-01 19:06:32 +05:30			`- FragmentId`
			`- EventIndex`
add todo for fragments 2019-04-18 23:50:23 +05:30			`- write fragmentStore`
			`- adapt timelineStore`
			`- adapt persister`
			`- persist fragments in /sync`
			`- load n items before and after key`
			`- fill gaps / fragment filling`
			`- add live fragment id optimization if we haven't done so already`
			`- lets try to not have to have the fragmentindex in memory if the timeline isn't loaded`