v0.23.1 - 26th September 2019

Ensure sharp.format.vips is present and correct (filesystem only). #1813

Ensure invalid width and height provided as options to resize throw. #1817

Allow use of 'heic' and 'heif' identifiers with toFormat. #1834 @jaubourg

Add premultiplied option to composite operation. #1835 @Andargor

Allow instance reuse with differing toBuffer options. #1860 @RaboliotTheGrey

Ensure image is at least 3x3 pixels before attempting trim operation.