Extend HTMLWriter: flush the stack, more values for attribute(..)

Change-Id: I733426ba5f82ee25751387f88942dbc66689821d
html: line break <br/> - use XML style single element declaration

Change-Id: I2e2b7fb85bd272a45d973c29f792c54aa7be0a82
html: add applyEvents to HTML output

Change-Id: I8cc2d752673254c0f23f63030a8fa7d4d288c0a9
html export: rework image output to use HTML writer

Change-Id: Iead3f0f49b93453bd45f07f047978cb92d279d21
Test HTML export of images & image properties.

Change-Id: Ib0bffab0e653dc9ad0cc5367fdbc6bdee02181d2
Convenient function to compress a Graphic to PNG image

Change-Id: I3d30dd4337b6bd3b5b0c7cdf97a8787c4bc37fa3
fdo#62104 Optimize thumbnail size by using PNG8 and other tricks

Change-Id: I54ece4a1977fe93c0e7bbb11774bd8657912c6bb
werror: ‘nDirection’ shadows a member of 'this'

Change-Id: Idb56ef8327164f22379b732f9507e0b255b0998c