BS-1379, update exporter to have the type on left operand and to export transient data as expression type
BS-1379, fix export of string indexe expression + add unit tests
Merge branch 'master' into BS-1379_TransientData

Conflicts:
	bundles/plugins/org.bonitasoft.studio.common/src/org/bonitasoft/studio/common/ExpressionConstants.java
	bundles/plugins/org.bonitasoft.studio.engine/src-test/java/org/bonitasoft/studio/engine/export/EngineExpressionUtilTest.java
	bundles/plugins/org.bonitasoft.studio.engine/src/org/bonitasoft/studio/engine/export/EngineExpressionUtil.java
	bundles/plugins/org.bonitasoft.studio.engine/src/org/bonitasoft/studio/engine/export/switcher/AbstractSwitch.java
	bundles/plugins/org.bonitasoft.studio.engine/src/org/bonitasoft/studio/engine/export/switcher/FlowElementSwitch.java
	bundles/plugins/org.bonitasoft.studio.exporter/src/org/bonitasoft/studio/exporter/form/FormsExporter.java
adapt after engine merge
Merge branch 'master' into 'BS-1379_TransientData'
fix forms exporter tests
Merge branch 'master' into 'BS-1379_TransientData'
Merge branch 'master' into 'BS-1379_TransientData'
BS-1379, fix studio export of business data operations
BS-1379, add validation rul for invalid operations
BS-1379, do not mark error if the wrong operation in on a read only widget
Merge branch 'master' into 'BS-1379_TransientData'
Merge branch 'master' into BS-1379_TransientData

Conflicts:
	bundles/plugins/org.bonitasoft.studio.exporter/src/org/bonitasoft/studio/exporter/form/FormsExporter.java
	bundles/plugins/org.bonitasoft.studio.validation/messages.properties
	bundles/plugins/org.bonitasoft.studio.validation/src/org/bonitasoft/studio/validation/i18n/Messages.java
Merge branch 'master' into 'BS-1379_TransientData'
Merge branch 'BS-1379_TransientData' into 'master'