Width and height transform tools

Layers with adjustable width and height are now indicated by a centered dot on each side; use the dots to adjust the size property rather than the scale property, and better maintain shape features.

Fixes & Improvements

• Added double strokes to the gradient steps to easily distinguish color.
• Improved the Eyedropper tool to make it work with gradient steps.
• Updated some minor copy and made small design tweaks for clarity.
• Fixed a bug that allowed ⌘ + Z to move between and overwrite projects.
• Fixed a bug that caused the value graph to automatically switch to the velocity graph when modifying easing.
• Fixed a bug with Linear and Radial gradient modes.
• Fixed a bug to make the “Accept Invite” page work for logged-in users.
• Fixed a bug that sometimes caused audio to not export correctly.
• Fixed a bunch of bugs with effects depending on the order they're added in and what is switched on or off.
• Fixed a bug with the Pinch/Warp effect when applied to the background.