Add plugins/minimize.sh

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+# minimize.sh --- Minimize CSS/JS assets using sed
+
+# from https://www.tero.co.uk/scripts/minify.php
+
+### Commentary:
+
+## How it works
+# It removes comments from CSS and Javascript files using sed. First it replaces
+# /**/ and /*\*/ with /~~/ and /~\~/ as these comments are used as CSS hacks and
+# should stay in the file. Then it removes /*...*/ style comments on single
+# lines (from Javascript and CSS files - this was adapted from a common PHP
+# regular expression for removing CSS comments). Then it removes // style
+# comments from Javascript files (unless they are preceded by a : which means
+# they might be web links). (It's done in this order so that comments like
+# /*...//...*/ get removed properly). Then it replaces all newlines with spaces
+# and removes /*...*/ style comments again (this time over multiple lines). Then
+# it puts the /**/ and /*\*/ CSS hacks back in. Then it replaces multiple spaces
+# with single spaces. Then it removes spaces before [{;:,] and then spaces after
+# [{:;,].
+
+## Problems - quotes and Ajaxy functions
+# This script does not ignore things in quotes. So if you have a comment
+# inside a quote in a Javascript file, such as document.writeln ('//This
+# is a comment');, the script will remove everything from the // and
+# cause a Javascript error. Also, all lines of Javascript must end with
+# a semicolon. This can be an issue with libraries which declare
+# functions on a line but don't end the line with a semicolon (as is
+# common in Ajax and JQuery scripts). For example, in: load : function
+# (url,callback,format) {...} http.send(nul);, there should be a
+# semicolon after the function definition. This is legal Javascript if
+# there's a line break, but causes an error once minimised without the
+# line break.
+
+## The Function
+minimize() { # minimize < INPUT
+    sed -e "s|/\*\(\\\\\)\?\*/|/~\1~/|g" \
+        -e "s|/\*[^*]*\*\+\([^/][^*]*\*\+\)*/||g" \
+        -e "s|\([^:/]\)//.*$|\1|" -e "s|^//.*$||" |
+        tr '\n' ' ' |
+        sed -e "s|/\*[^*]*\*\+\([^/][^*]*\*\+\)*/||g" \
+            -e "s|/\~\(\\\\\)\?\~/|/*\1*/|g" \
+            -e "s|\s\+| |g" \
+            -e "s| \([{;:,]\)|\1|g" \
+            -e "s|\([{;:,]\) |\1|g"
+}