SolidPython missing support for recent OpenSCAD statements in 2014.03

[etjones]

Looking at the OpenSCAD cheatsheet, there are a few statements ('text', 'offset') not supported in SolidPython. Putting this here as a placeholder to remind myself to add these pieces

[ehooo]

Also new 'concat', 'let' and 'assign'.

[etjones]

From the OpenSCAD 3/2015 Release Notes:

Language Features:

• Added text() module for 2D text
• Added offset() module for 2D offsets
• Added list comprehensions and let()
• Added concat() function
• Added chr() function
• surface() can now take PNG images as input
• min() and max() can now take a vector argument
• 2D minkowski can now handle polygons with holes
• Variables can now be assigned in local blocks without using assign()

[etjones]

All the features mentioned here have either been added (text(), offset()) or are machinery in OpenSCAD that's already available in Python (let(), assign()). Call it good for now