added core ref line trait, and widget and set core level to update to it
fix trace tool so to handle index out of bounds when tool moves of edge
cleaned up some formatting, added survey save_to_disk method -- not implemented
fixed a couple errors in depthline view
fix bug in apply to group
fix bug in apply to group
fix not edit locked surfaces
added docx user manual to repository so that any user can update it.
updated user manual
add stop control to msg dialog
commented some debug code
pep8 / whitespace
replace "h5" file with a project directory that contains multiple files
splitting the commonly-written data (pick lines) into separate files should
allow simultaneous users to work on the same survey (e.g. on a shared network
drive) without colliding very often
wrap writes to hdf5 files with lockfile to avoid corruption by concurrent writes
(e.g. multiple users running with project files on a shared network drive)
whitespace
set survey_line.project_dir correctly
save depth lines and preimpoundment lines when edited
save survey line string properties when saving the survey line
fix: open survey line attrs file in write mode - appends gum things up
save/load survey line masks to/from file backend