Continued working on q_response() and e_response().
Fixed small error in NEWS.
Simplified the operators to avoid repeated code across operators. Functions con the cleaned in the same way.
Hopefully now debugged. Increased version number.
Replaced many uses of invisible() with return() as the recent change was confusing, and not following the usual R behaviour. Updated the User Guide.
Added options to change the default behaviour of operators and functions.
Debugged of new options and new operators code. Thorough update of User Guide.
With a lot new and complicated functions, it is likely that some bugs still remain.
More debugging, and added absorbance functions.
absorbance_spct() still not working correctly.
Fixed several bugs and simplified code in some of the intergration and average functions. Also fixed bug in trim_spct related to sttributes.
Overhauled irrad, response, reflectance, transmittance and absorbance families of functions. Now they all have a 'quantity' parameter, and they have consistent interfaces.

Debugged also earlier changes, and once more edited the User Guide.

Increased version to 0.5.0 as some of these changes may affect user code.

Moved find_peaks(), get_peaks() and get_valleys() from photobiologygg to this package.
Added missing! response.spct() function.
Added missing response.spct() function.
Fixed two bugs in new_waveband: 1) wb.label was not set when wb.name was auto-generated!
2) Both hinges were on the outside of the waveband, giving trouble with wavebands sharing their limits.
More bugs squashed in code and docs. Docs still need cleaning.
Added missing response.spct() function.
Fixed two bugs in new_waveband: 1) wb.label was not set when wb.name was auto-generated!
2) Both hinges were on the outside of the waveband, giving trouble with wavebands sharing
their limits.

Added new function trim_waveband().
Editted irrad(), response(), transmittance(), absorbance(), reflectance(), ratio() functions
for spectra to use this function internally, and gaining the wb.trim parameter, which defaults
to FALSE. Fixed small numeric errors in the creation of the waveband for the whole spectrum.