add merge to ImageOptions
add merge_method to config
enable composite image merging
always use global image options
check for alpha_composite support
disable alpha composite test when Image.alpha_composite is not available
raise nose.plugins.skip.SkipTest when Image.alpha_composite is not available
work in progress
add tests; support for default values
improved dimensions in wmts kvp requests
add checks for KVP requests
use lowercase dimension names
ignore case in WMTS KVP dimensions
check dimensions in WMTS capabilities
except different casing
allow . and : in WMTS RESTful layer, tilematrixset and styles
prevent caching of dimension layers
document WMTS dimension support
Merge branch 'master' into wmts-dimensions
update formatting of wmts dimensions doc