Only use strokeWidth in object scaling when stroke is set.

Also only use half of the strokeWidth, this matters especially when the strokeWidth is large compared to the object size.
Merge branch 'master' into scaling-strokewidth-fix
Update parser.js
Update group.class.js

added managing of  originX/Y to group.
Fix opacity for fabric.Text and fabric.IText
Update group.class.js
Merge pull request #1766 from Kienz/textOpacity

Fix opacity for fabric.Text and fabric.IText
Update group.js
Update canvas_grouping.mixin.js

Removed forced originX/Y from dynamically created groups
Update group.class.js
Update group.js
Merge pull request #1759 from asturur/fix-symbol-render

Fix symbol render
Update group.js
Merge pull request #1644 from ChrisBuergi/scaling-strokewidth-fix

Scaling strokewidth fix
Merge pull request #1765 from asturur/fix-for-group-position

Fix position of group for originx/y different from center.
Add `fabric.Image.setSrc`
Fixed spelling
Merge pull request #1768 from Kienz/setSrcImage

Add `fabric.Image.setSrc`
Update text.js
Merge pull request #1772 from asturur/master

Fix angle value. Closes #1251