Rename actions folder as scripts

It's clearer this way.

.github/scripts/install.sh

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+#!/bin/bash
+install -d /usr/local/bin/ /usr/local/share/man/man1/ /usr/local/share/man/man5/ /usr/local/share/man/man7/
+install -s -m 755 rgbasm rgblink rgbfix rgbgfx /usr/local/bin/
+install -m 644 rgbasm.1 rgblink.1 rgbfix.1 rgbgfx.1 /usr/local/share/man/man1/
+install -m 644 rgbds.5 rgbasm.5 rgblink.5 /usr/local/share/man/man5/
+install -m 644 rgbds.7 gbz80.7 /usr/local/share/man/man7/

.github/scripts/install_deps.sh

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+#!/bin/bash
+set -e
+
+case "${1%-*}" in
+	ubuntu)
+		sudo apt-get -qq update
+		sudo apt-get install -yq bison libpng-dev pkg-config
+		;;
+	macos)
+		brew install bison libpng pkg-config md5sha1sum
+		# For the version check below exclusively, re-do this before building
+		export PATH="/usr/local/opt/bison/bin:$PATH"
+		;;
+	*)
+		echo "WARNING: Cannot install deps for OS '$1'"
+		;;
+esac
+
+bison --version
+make --version
+cmake --version

.github/scripts/mingw-w64-libpng-dev.sh

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+#!/bin/sh
+
+set -e
+
+pngver=1.6.37
+arch="$1"
+
+## Grab sources and check them
+
+wget http://downloads.sourceforge.net/project/libpng/libpng16/$pngver/libpng-$pngver.tar.xz
+wget http://downloads.sourceforge.net/project/apng/libpng/libpng16/libpng-$pngver-apng.patch.gz
+sha256sum -c .github/scripts/mingw-w64-libpng-dev.sha256sums
+
+## Extract sources and patch them
+
+tar -xf libpng-$pngver.tar.xz
+gunzip libpng-$pngver-apng.patch.gz
+
+# Patch in apng support
+env -C libpng-$pngver patch -p0 ../libpng-$pngver-apng.patch
+
+## Start building!
+
+mkdir -p build
+cd build
+../libpng-$pngver/configure \
+	--host="$arch" --target="$arch" \
+	--prefix="/usr/$arch" \
+	--enable-shared --disable-static \
+	CPPFLAGS="-D_FORTIFY_SOURCE=2" \
+	CFLAGS="-O2 -pipe -fno-plt -fexceptions --param=ssp-buffer-size=4" \
+	LDFLAGS="-Wl,-O1,--sort-common,--as-needed -fstack-protector"
+make -kj
+make install

.github/scripts/mingw-w64-libpng-dev.sha256sums

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+10d9e0cb60e2b387a79b355eb7527c0bee2ed8cbd12cf04417cabc4d6976683c  libpng-1.6.37-apng.patch.gz
+505e70834d35383537b6491e7ae8641f1a4bed1876dbfe361201fc80868d88ca  libpng-1.6.37.tar.xz