Code/tutorial for generating master Excel sheets (Issue #51)

See merge request !30

Deleted the terminal symbols, changed some line
breaks

Line breaks, code formatting, etc. All minor.

write_master.py creates a master Excel file for
automated DLB runs from a series of text files.
See usage and other notes in function doc string.

Deleted step 6 (Issue #52 main fork)

See merge request !29

Step 6 in "Getting Started with DLBs" was actually
unnecessary, so I deleted it.

Merge of dlc_highlevel_support_for_flex to master

See merge request !28