Revert "Duration and Frequency to float type"

This reverts commit 88eb49ff52d28d71b298bae3f838baaf020b09cd.
Use ints in buzzer functions
Remove some lpc17 dependencies
Test build without FreeRTOS
Introduce light-weight task architecture
Fix up problems with task params type
Merge branch 'edge' of https://github.com/bobc/R2C2_Firmware into edge
Detangle platform specific code
Split platform code out
Update crossworks project
Fix TaskCreate definition; restore systick handler
Add simple heap manager
Move linker script to arch/...
Separate board and platform build
Merge branch 'edge' of https://github.com/bobc/R2C2_Firmware into edge
Tidy up HAL
Move sdcard.* to libs/FatFs
Make SD/FatFs code dependent on HAVE_FILESYSTEM flag to reduce memory footprint for systems without SD card;
abstract some more platform dependencies
Update readme
Merge branch 'edge' of https://github.com/bobc/R2C2_Firmware into edge