More filesystem API

[koolkdev]

I added the functions: FSA_ChangeOwner, FSA_OpenFileEx, FSA_ReadFileWithPos, FSA_WriteFileWithPos, FSA_AppendFile, FSA_AppendFileEx, FSA_FlushFile, FSA_TruncateFile, FSA_GetPosFile, FSA_IsEof, FSA_RollbackVolume, FSA_GetCwd, FSA_MakeQuota, FSA_FlushQuota, FSA_RollbackQuota, FSA_RollbackQuotaForce, FSA_Rename, FSA_ChangeModeEx

I did some "space" optimization to be able to fit all those new functions in the same small space.

I changed many things but I didn't break any existing IPC call. (but I haven't tested everything after those changes)