Add output recipes

These recipes are required to support **Sketch > Export compiled
Binary**. See:

https://github.com/arduino/Arduino/blob/1.8.1/hardware/arduino/avr/platform.txt#L74-L76

https://github.com/arduino/Arduino/blob/1.8.1/hardware/arduino/sam/platform.txt#L86-L88

Author: per1234

digistump-avr/platform.txt

@@ -55,6 +55,10 @@ recipe.objcopy.eep.pattern="{compiler.path}{compiler.objcopy.cmd}" {compiler.obj
 ## Create hex
 recipe.objcopy.hex.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.hex"
 
+## Save hex
+recipe.output.tmp_file={build.project_name}.hex
+recipe.output.save_file={build.project_name}.{build.variant}.hex
+
 ## Compute size
 recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf"
 recipe.size.regex=^(?:\.text|\.data|\.bootloader)\s+([0-9]+).*

digistump-sam/platform.txt

@@ -74,6 +74,10 @@ recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.f
 ## Create output (.bin file)
 recipe.objcopy.bin.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.flags} {compiler.elf2hex.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.bin"
 
+## Save hex
+recipe.output.tmp_file={build.project_name}.bin
+recipe.output.save_file={build.project_name}.{build.variant}.bin
+
 ## Compute size
 recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf"
 recipe.size.regex=\.text\s+([0-9]+).*