Fix StrToInt64

Added unit test for 7 digits,
Before:
Amount detected: 4  - Pass converting from 0.00000004
Amount detected: 4  - Fail converting from 0.0000004
Amount detected: 40000  - Pass converting from 0.0004
After:
Amount detected: 4  - Pass converting from 0.00000004
Amount detected: 40  - Pass converting from 0.0000004
Amount detected: 40000  - Pass converting from 0.0004