Implement tree-based state system

Ref #10
StateHistorySink: actually write intervals
builder: fix state changes count not sent
qtibeeprogress: default log level: INFO
StateHistoryBuilder: add .delo extension to history file
builder: create non existing directory with -f
providers: linux: prefix paths with "linux"
common: state: nullify all nodes when closing SH

Closes #13
contrib: update libdelorean
Run Cppcheck and fix stuff
Support debug and release build modes
providers: linux: implement onSoftIrqEntry()
providers: linux: implement onSoftIrqExit()
providers: linux: implement onSoftIrqRaise()
common: state: explicit visitor/state node method names
providers: linux: partial sched_switch() implementation
providers: linux: implement onSchedSwitch()
linux: proviers: register sched_wakeup*
providers: linux: implement onSchedProcessFork()
providers: linux: ensure linux node, implement onSchedProcessFree()