Add new support for Kromek SPE files

[RLumSK]

The Kromek CZT detectors export a rather unusual ASCII format SPE files that cannot be imported with 'rxylib'. Adding this functionality here was easier than writing C++ code.

Notes

• @nfrerebeau I've added myself as an author to the package. If you feel that this too much, please just degrade me to contributor.
• This is a beta version implementation; I have to work more with the package, eventually I will update this implementation.

Description

• ad update to read.R with code for the import
• up method definition to handle SPE files
• ad NEWS
• ad extdata/Kromek_CZT.spe file
• up DESCRIPTION and add me as author
• up manual
• ad test for the import
• up test fpr the calibration
• up fact splot checks

Related Issue

Not applicable

Example

spe_file <- system.file("extdata/Kromek_CZT.spe", package = "gamma")
spe_spectrum <- read(spe_file)

[nfrerebeau]

@RLumSK cool! Do you need a new (CRAN) release with this new functionality, or can it wait until this fall?

[RLumSK]

Thanks @nfrerebeau. No, it can wait until fall. I am using it actively now, but before the manuscript work is done it may take some time (it can be release later regardless). More time is better, because it allows to spot some additional bugs.

• For instance, I realised that the GammaSpectrum-class does not hold a slot for comments/description. This we may want to add.
• I also have to double check the 'real time' and 'live time' to ensure that I did not mix the two up (only the new format)