Add functionality to create masks for within-transect (good regions)

[valentina-s]

This can take several forms but it slightly depends on how people have annotated individual breakpoints:

• start transect
• break transect
• resume transect
• end transect

Usually those should be annotated with log lines, but sometimes it can be thin boxes, or within-transect boxes. One approach is to create an intermediate table with time stamps for the staring and ending times and create the mask based on it.

[leewujung]

I wonder if this should be something like an external script we use for the hake survey data with the start/end times, it seems cleaner to have it separate from the main echoregions functions.

[valentina-s]

Right now it is external, but we should possibly have some functionality to handle log-type regions in echoregions since this is one of the types of regions.