[misc] refactoring and cleanup - part 1

* add stdfn.c and move the relevant standard calls there
* move most of GetDriveInfo() to drive.c
* rename IDC_DOS/hDos to IDC_BOOT/hBoot
[misc] refactoring and cleanup - part 2

* add GetResource() function call to handle resource loading and
  revert 98ff7a931a11a0f7cb25d1533e872c5efd68039d
* add separate BootCheck() call
* better handling of passes tooltip
* remove superfluous backslashes
* fix standalone EFI support
* add GPL v3 license file and update README.txt