This might do what you want. It’s meant to be invoked as a command line tool per file and it sends its results to STDOUT. It’s essentially a one-liner unrolled to a script. You can put in an -i flag to edit the file in place but this is risky. Don’t do it unless you have backups and are going to check everything. Save it as, space-collapser.pl or whatever you like–

Update: I don’t have a lot of experience with WIN on this front… I’m, not sure this will work for you as is.

#!/usr/bin/env perl -0777 -p
# -0777, idiom for "slurp" mode.

# Strip all trailing spaces including blank lines with spaces.
s/[^\n\r\S]+(?=\r?\n)//g;

# Reduces all triple or greater line spacing to double spaced lines.
s/((?:\r?\n){2})(?:\r?\n)+/$1/g;

# -p print at the end of each implicit loop.
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