Development sk (#135)

* Update 3D to 2D projection

* Fix LengthUnit error

* update MetaDataClass Set method

* remove ProbeClass.m.bak file

* fix bugs in MetaDataTagsClass and SnirfClass

* Make circular 2D probe pos range -1 to 1

* Fix merge issues with fig file

* Fix probe3dto2d issue when snirf file has incorrect landmarklabels

* Generate source2D and detector2D positions same time instead of seperately when labelmark3D are not available

* Minor changes to make code clean