Change default extensions for amira landmarks

* .landmarkAscii is what Amira 5.6.0 uses
function to read in Fiji format landmarks

* as produced by http://fiji.sc/Name_Landmarks_and_Register plugin
rename landmarks test file
don't name the rownames for fiji landmarks
test reading fiji landmarks
specify tolerance
test reading file with just 1 landmark
remove unused read.landmarks.fiji Verbose arg
Add is.fijilandmarks

* won't be exported
register fijilandmarks format
rename *.amiralandmarks -> *.landmarks.amira

* this is the strategy we have taken with other file formats
* with a view to making single public read/write.landmarks
  functions
Function to identify cmtk.landmarks files
Register cmtklandmarks format
Add generic read.landmarks function

* expect to make other read.landmarks functions private
test generic read.landmarks
*.cmtklandmarks->*.landmarks.cmtk

* again for consistency
* expect to hide them anyway soon
Add generic write.landmarks function

* including full docs
fix some buglets in write.landmarks

* nb some other functions presently won't overwrite - need to check that.
Remove Force parameter from write.landmarks.cmtk

* will deal with this in write.landmarks
No longer export *.landmarks.cmtk