Changed behavior of VirtualBlock::Allocate, FreeAllocation: VirtualAllocation::AllocHandle = 0 (not UINT64_MAX) now means null allocation.
Ported linear allocation algorithm from VMA.
Renamed VIRTUAL_ALLOCATION_INFO members to uppercase Offset, Size.
Fixed D3D12MA_DEBUG_MARGIN not to be applied to virtual allocator.
Added test for D3D12MA_DEBUG_MARGIN (ported from VMA).
Code mostly by @medranSolus
Updated and rebuilt documentation.