devpanel: fix crash on inspecting svg elements
test for basis.layout.getViewportRect added
new basis.dataset.Merge#addSource/removeSource, add spec
field.js: fix url regexp
Calendar test for issue https://github.com/basisjs/basisjs/issues/16
dataset.Merge: various fixes, extend tests
data.dataset: Merge setSources/clear, optimize event count, extend tests
rename basis.data.AbstractDataset -> basis.data.ReadOnlyDataset
ui.calendar: rework section node creation and small refactoring (fixes #16)
layout: fix getViewportRect adds page scroll offset twice
1.2.3
Merge branch '1.2.3'
core: implement virtual resources
template: inline `<b:style>`
Merge branch 'anonymous-resources' into 1.3.0
core: add sourceURL for css resources
Merge branch 'master' into 1.3.0

Conflicts:
	src/basis.js
data.dataset.Subtract: use resolveDataset for minuend and subtrahend
basis.ui.calendar: deprecate Calendar#sections, manipulate sections by childNodes now
basis.template: auto close html singleton tags (like `<input>`, `<br>` etc)