icons: Unused CheckStyleCache.

Change-Id: I9097b2704b7a961f448c58572f091f335847e951
icons: m_cacheIcons is always true, kill it.

Change-Id: Ie63f8780093a2605ecd4d1e80ccb05e16b486cf1
icons: Kill an unused function + bring some consistency to the file.

Change-Id: I346d751cef124b534784f0b3b335c9578c56e024
icons: Store paths of more styles at the same time.

Change-Id: I9a13aa3ed928b989eaa2b2da8d1acfc5a37f506e
icons: Even the cache and links are now stored per-style.

Change-Id: I7d2bfd3e8aa102e88c107de445fa77c004867fe7
icons: Implement the fallback mechanism for icons.

When an icon is not found in eg. images_sifr.zip, search it in
images_tango.zip, etc.

Change-Id: I8af952a1bd8e9e02531f84012e8ce39e75422313
icons: Package only the icons that are in the theme.

The fallback is now implemented directly in vcl, no need to waste space any
more.

Change-Id: Ia027fda5e92d2bac7369139f3277d73b0521bef2
icons: Kill now irrelevant warning.

Change-Id: I2ce348fe97cfc0fdaf1ad5e1063a28d069accdf5