refactored erlog_memory
refactored, but not tested
Merge remote-tracking branch 'origin/master' into develop

Conflicts:
	src/libs/external/db/erlog_db.erl
Merge remote-tracking branch 'origin/master' into develop
Merge remote-tracking branch 'origin/master' into develop
Merge remote-tracking branch 'origin/master' into develop

Conflicts:
	src/io/erlog_file.erl
fix use
fix db-next
fix case clause when using db impl
fix warning
fix db passing when fail in clause
export debug fun
fix float negative numbers
improve concat
Merge remote-tracking branch 'origin/master' into develop

Conflicts:
	src/core/erlog.erl
fixed merge with master
Merge branch 'master' into develop
improve string libs
fix substring
made substring tryadd