[Plugin: Front-end Editor] Activate Error: Parse error: syntax error, unexpected ‘?’, expecting ‘(‘

I downloaded the current front-end Editor plugin version from your site, and when trying to activate rec’d this error message on the Plugin page:
Plugin could not be activated because it triggered a fatal error.
(in window:)Parse error: syntax error, unexpected ‘?’, expecting ‘(‘ in /homepages/3/d325557441/htdocs/website/wp-content/plugins/front-end-editor/front-end-editor.php on line 73
Line 73 is:
‘class’ => FEE_Core::$options->chunks ? ‘FEE_Field_Chunks’ : ‘FEE_Field_Post’,

I searched this forum posts, and tried downloading the Development version. Same thing happened, only the error is on line 81 now. (same line content)

I tried adding the line to get PHP version into my wp-content.php like your FAQ suggests- but then I couldn’t even log into my admin page.

FYI: My host/server is 1and1.com, and I have had to do fixes for my theme to get it to recognise that it’s php5. Could this be the issue?

Thanks for your help, your plugin looks amazing, I’d love to use it! Jana