1.51-b1

	- Updated 'calibrate' output to include a brief explanation of the
	various flux measures in the output file when a new output is created.

	- Mask files now use epoch information. Also made parsing more robust.

	- New option '-noise=' added to imagetool and show to define what
	noise estimate to use. Values are either 'data' for reduction weights
	or 'image' for noise estimates based directly on the image.

	- New option '-changeKey=key:value' added to imagetool and show,
	allowing to change any FITS header entry. This is an expert option.
	Use only if you know what you are doing!!!

	- New option '-printHeader' added to imagetool and show to print the 
	FITS image header.

	- Final map can also be re-weighted with the MAP_FINAL_REWEIGHT boolean
	key or -reweight= boolean option. By default final reweighting is 
	disabled, as scan weights should be sufficient. The weight adjustment
	factor is recorded in the FITS image under the 'XWEIGHT' key.
	
	- Further tweaked configuration files for optimal performance...

	- Fixed crashing under -rounds=0 (direct map reconstruction). 

	- Improved Image FFT (in show). Now properly ordered and normalization
	fixed. (FFT can be obtained bt pressing 'T' in the image window...).

	- Maximum-Entropy modelling introduced to source map extraction. MEM
	modeling can be selected by MAP_ESTIMATOR key or -Emap= flag to the
	value "MEM". MEM_LAMBDA key and -lambda= flag set the MEM lambda 
	parameter value. Lambda = 0 reporduces the maximum-likelihood model,
	while larger lambda values give prominence to the maximum entropy
	condition. Typically lambda values between 0-1 should be used...
	MEM enforces a positive (and zeroes) image, and the noise properties
	of the background are non-trivial. However, MEM should produce
	stunning images of sources in good signal-to-noise conditions 
	(SNR > 10 typically), especially for galactic images...
	When MEM estimators are used internal map smoothing will be disabled.
	The removals of map negatives is also redundant given the positive
	image, and will also be disabled for MEM.

	- Debugged the way -smooth= flag was parsed. -smooth=off or 
	-smooth=always:off wasn't correctly parsed.

	- MAP_TURN key and -Imap= option now understands new argument 'last',
	which delays source extraction until the very last iteration. This 
	may be desirable for getting the cleanest possible maps (e.g. deep 
	reductions). Accordingly, deep.cfg (invoked by -deep) has been 
	adjusted to implement this delay. Also, if the 'auto' is set (default)
	the source will be delayed if the model is at the end of the pipeline
	(with no flux models to follow it).

	[ Some cleanup work in ReductionTool and ReducedData classes. ]

