Improved Feature pages

Smaller feature-page screenshots, and new Favicon Generator and E-Signatures pages

Product screenshots on feature pages are shown smaller with a shadow, the Forms page opens on the form builder, and the Favicon Generator and E-Signatures pages were rewritten with new screenshots.

Product screenshots on feature pages are now held to 1080 pixels wide at most, centred, with the same shadow as the homepage, so they read as pictures of Magpie rather than the interface itself.

The Forms page now opens on the form builder. The respondent preview screenshot, with its preview banner, was removed.

Rewrote the Favicon Generator and E-Signatures feature pages from the current product and Help, with new screenshots.