Use custom Makefile

Using a custom Makefile results in a huge increase in compilation speed. I did not implement building of the BSP as it is only done rarely.

This makefile provides the following targets : 
* `make all` compiles and links the ELF file. It also "patches", which is required by Altera's HAL
* `make clean` removes all compiler output files.
* `make load` Compiles the program if necessary and downloads it onto target (was called download-elf by Altera, but moar chars to type).