Fix parsing of values on new lines by enabling empty lines in multiline values by default

[Copilot]

This PR fixes an issue where the configparser failed to parse values that are placed on a new line after the key, particularly when there are empty lines between the key and value.

Problem

The library was not correctly handling cases like:

[section]
option3 =
    value3

Where parser.Get("section", "option3") would return an empty string instead of "value3" when there were empty lines between the key and the multiline value.

Root Cause

The parsing logic would terminate multiline value parsing when encountering empty lines, unless the AllowEmptyLines option was explicitly enabled. This behavior was counter-intuitive for users who expected standard configuration file multiline value behavior.

Solution

• Enable the emptyLines option by default in defaultOptions()
• Update the existing test case that expected the old behavior to reflect the new, more intuitive behavior
• Add a comprehensive test case to validate newline value parsing scenarios

Impact

This change makes the library more user-friendly by allowing empty lines in multiline values by default, which aligns with common expectations for configuration file parsing. While this is technically a breaking change in behavior, it makes the library work as users intuitively expect.

All existing tests continue to pass, and the core functionality (interpolation, basic parsing, etc.) remains unchanged.

Fixes #14.

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[Copilot]

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[emar-kar]

Hello again. Great to see new updates. This catch is interesting, as I see python's version also enables it by default. Maybe it's also a valid moment to get back to the python version and confirm that other flags are working the same way?

[emar-kar]

Probably better to change to will not miss?

[bigkevmcd]

@copilot can you address this feedback?

[emar-kar]

I guess this change should also lead to deprecation of the AllowEmptyLines, since this option will be ON by default and introduction of NoEmptyLines or something similar to bring back old behavior?

[bigkevmcd]

@emar-kar Thanks for the reminder about this - I gave this task to Copilot to figure it out and then forgot about it😄