exact sin/cos and eliminated duplicate args computations:
1) eliminated duplicate arguments computations for most of builtin functions (except serach & lookup);
2) provide exact results of sin or cos whenever possible like cos(90)
Fix keyboard shortcuts in automatically generated actions (fixes #408).

Having our own "copy" menu did cause the automatically generated action
of the QTextEditor used as console to drop the CTRL+C link. Using the
WidgetWithChildrenShortcut settings seems to fix that for Qt4 and Qt5.
remove /opt/qt5 hack in setenv script. (distros have their own way to specify)
default to qt5 for MXE cross build for Win
Merge pull request #770 from openscad/copy-paste-fix

Fix keyboard shortcuts in automatically generated actions (fixes #408).
change max qt version in README to support qt5
qt 5.0->5.2
remove #ifdefs for eigen version 2 ( see issue #532 )
Merge branch 'master' of github.com:openscad/openscad
build linux snapshot with QT5 by default
Merge pull request #769 from tim-caper/builtin2

exact sin/cos and eliminated duplicate args computations
Updated Mac setenv script
Sync two remaining test cases after merging unstable. Fixes #758
Switch from #define guards to #pragma once

As well as a few whitespace cleanups
Various whitespace fixes
clipper-utils: Fix signed-ness warning
GeometryEvaluator: Fix signed-ness warnings
low-level optimization to reduce stack usage & accelerate calculations
fixup issue 766
Avoid leaving the first empty document window when opening a file in MDI mode