Move to template format instead of cat-EOF

Simplifies the scripts and adds the ability to easily and cleanly change
the contents of these files without dealing with escape characters, etc.

templates/boot.pxe

@@ -0,0 +1,24 @@
+#!ipxe
+
+# Set global variables
+set root-url tftp://${next-server}
+set kernel vmlinuz
+set initrd initrd.img
+
+# Set kernel command line parameters
+set imgargs-base vga=normal nomodeset boot=live components ethdevice-timeout=600 timezone=America/Toronto fetch=${root-url}/filesystem.squashfs username=root
+set imgargs-pvcinstall pvcinstall.preseed=on pvcinstall.seed_host=${next-server} pvcinstall.seed_file=/host/mac-${mac:hexraw}.preseed
+
+# Load per-host kernel command line parameters (should contain ${imgargs-host} if present)
+chain --autofree ${root-url}/host/mac-${mac:hexraw}.ipxe ||
+
+# Set default menu options
+set menu-default pvc-installer
+set submenu-default pvc-installer
+
+# PVC installer menu option
+:pvc-installer
+kernel ${root-url}/vmlinuz
+initrd ${root-url}/initrd.img
+imgargs vmlinuz ${imgargs-host} ${imgargs-base} ${imgargs-pvcinstall}
+boot