Legacy "main" database files need to be read as ANSI code page 1252

[delphidabbler]

Main database file reader needs to be revised to use ANSI code page 1252 instead of Default encoding in TMainDBFileReader.GetFileEncoding.

Encodings are disposed of safely, so no worries about a memory leek using a non built in TEncoding.

Why is this necessary?

The current code assumes that non-Unicode database files can be read using the Default encoding, because that's how they were originally written.

However, all the "main" database files were created in the UK where the default ANSI code page is 1252. Reading back these files in locales where the default ANSI code page is different may cause problems.