add fullscreen mode to vellum
add ability to resize the left pane
set full screen icon initial state correctly
get rid of double scrolling on mouse wheel

if your mouse is over the one of vellum's scrollable sections
and you use your mouse wheel (or touchpad, etc.) to scroll
you no longer start scrolling the window when the pane reaches the top/bottom

up/down keys still have double scrolling behavior,
and you can still click the up down arrows on either scroll bar
for OS's that have that (i.e. most except macs)
Merge pull request #282 from dimagi/left-pane-resize

Resizable vellum anyone?
Merge pull request #281 from dimagi/fullscreen

Fullscreen vellum anyone?
add comment to double scrolling fix
Merge pull request #283 from dimagi/no-double-scrolling

get rid of double scrolling on mouse wheel
Refactor parser to allow plugin extensions
Move itemset parser extensions into itemset module
Consolidate <item> parsing logic
Move <repeat> parsing logic into group adaptor
Move read-only logic into control node adaptor
Merge pull request #284 from dimagi/model-repeat-parser-refactor

Model iteration parser refactor
Merge branch 'master' into hq-data-api