Finish the script to read FXT file and check its header.

Given the following script: TestFXTHeader.mq4, the goal is to finish the script which opens the FXT file and check its header.

The validation function is in place, there is only issue with CreateFileW and FileSeek which doesn't work properly.

As result, I'm expecting that FXT file would be open and ReadAndCheckHeader function will pass all the tests which are already there.

This should work in the recent MetaTrader 4 (e.g. build 971).