Fix get/set(PlayerTilePosition) offset by 1

[johnathanchann]

Related Issue

Fixes #30

Type of Change

• Offset getTilePosition by -1
• Offset setTilePosition by +1

Tested with test_suite

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2/2 Testing: full
2/2 Test: full
Command: "/mnt/c/Users/yeefh/documents/mcpp/build/test/test_suite"
Directory: /mnt/c/Users/yeefh/documents/mcpp/build
"full" start time: Jun 12 00:07 AEST
Output:
----------------------------------------------------------
[doctest] doctest version is "2.4.9"
[doctest] run with "--help" for options
===============================================================================
[doctest] test cases:  6 |  6 passed | 0 failed | 0 skipped
[doctest] assertions: 40 | 40 passed | 0 failed |
[doctest] Status: SUCCESS!
<end of output>
Test time =   0.92 sec
----------------------------------------------------------
Test Passed.
"full" end time: Jun 12 00:07 AEST
"full" time elapsed: 00:00:00
----------------------------------------------------------

End testing: Jun 12 00:07 AEST