kaleidoscope-builder: Do not hardcode the max program size

Instead of hardcoding the max program size, pick it out of boards.txt, like we
pick the device VID and PID.

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

bin/kaleidoscope-builder

@@ -30,8 +30,7 @@ firmware_size () {
 
     ## This is a terrible hack, please don't hurt me. - algernon
 
-    MAX_PROG_SIZE=28672
-
+    find_max_prog_size
     output="$("$@" | grep "\\(Program\\|Data\\):" | sed -e 's,^,  - ,' && echo)"
 
     PROGSIZE="$(echo "${output}" | grep "Program:" | cut -d: -f2 | awk '{print $1}')"

etc/kaleidoscope-builder.conf

@@ -26,6 +26,17 @@ fi
 # Shamelessly stolen from git's Makefile
 uname_S=$(uname -s 2>/dev/null || echo not)
 
+find_max_prog_size() {
+    VPIDS=$(${ARDUINO_BUILDER} \
+    -hardware "${ARDUINO_PATH}/hardware" \
+    -hardware "${BOARD_HARDWARE_PATH}" \
+    ${ARDUINO_TOOLS_PARAM} \
+    -tools "${ARDUINO_PATH}/tools-builder" \
+    -fqbn "${FQBN}" \
+    -dump-prefs | grep "upload\.maximum_size=")
+    MAX_PROG_SIZE=${MAX_PROG_SIZE:-$(echo "${VPIDS}" | grep upload.maximum_size | cut -d= -f2)}
+}
+
 find_device_vid_pid() {
     VPIDS=$(${ARDUINO_BUILDER} \
 		-hardware "${ARDUINO_PATH}/hardware" \