Add external avatar file check for missing files

[rica-carv]

Motivation and Context

External avatar files, when missing, give this output:

Description

Added code to revert to default avatar image, when external file is missing, output like this:

How Has This Been Tested?

Tested in e107 v2.3.3 clean install,
Output tested in admin area and in the front end (pics above)

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (a change to man pages or other documentation)

Checklist

• My code adheres to the e107 code style standard.
• I have read the contributing document.
• I have added tests to cover my changes.
• All new and existing tests pass.

[CaMer0n]

Thanks for this. Maybe I'm misreading it, but the file_exists() function in PHP does not work with remote URLs, so I'm not sure how this is working for you. ?

[rica-carv]

Thanks for this. Maybe I'm misreading it, but the file_exists() function in PHP does not work with remote URLs, so I'm not sure how this is working for you. ?

Sorry, im using localhost, so forgot it's a remote url. Just changed file_exists for fopen for remote url checking