mark_eye_data: Allows marking of eye data
In hejtmy/eyer: Loading and preprocessing of eyetrakcer data

Allows marking of eye data

1	mark_eye_data(obj, mark, times = c(), raw_times = FALSE)

`obj`	`EyerObject`
`mark`	string with the name of the mark
`times`	numeric(2) vector to define which part of the data to select
`raw_times`	commonly, the eyer data times are 0 based witht eh starting time being saved in `info$start_time`. Most operations are then calculated using these 0 based timings. If raw_times is set to TRUE, data are filtered with ackowledging obj$info$start_time.