Major Bessel filter rewrite and bugfix

Andy Leuckert (@anleu) is the main contributor to this release:

He fixed a bug which caused a sign inversion: 54e8e38

He provided new Bessel poles by using pre-calculated ones from scipy.
16ecc81

He has also added a lot of more unit tests which compare the scipy outputs with those of this library.

Thank you very much for this effort!

More unit tests

More tests have been added which test the 2nd order stages and the chain of 2nd order filters with realistic coefficients. The test case was generated cross platform with python scipy commands.

Filter parameters from python

For those who want to design the filters in Python can now enter the coefficients via the class SOSCascade. The coefficient arrays have the same order as generated by the scipy functions.

Range check bugfix

The cutoff frequencies need to lie between [0...fs/2[ where the Nyquist frequency is not included. Since the filter uses the bilinear transform the Nyquist frequency translates to an infinite frequency in the analogue domain so creates coefficients being NaN. Any out-of-range cutoff triggers now an ArithmeticException.

junit update

Updated to newest version of junit.

New maven release

This fixes an issue with a debug leftover and I also dropped the 3rd digit of the version number as the number of fixes has been really low.

Maven Central release version

This release marks the first release on Maven Central.
Note that the pom.xml has version number 1.0 and omits the third digit which is reserved for github related mini-edits and which have no impact on maven.

Released with documentation

On top of the javadoc one can now do "mvn site" to create web pages of the documentation.
No changes to the code base.

javadoc fixes and change of version numbering in pom.xml

Fixed a lot of javadoc issues in the source code.
Versioning numbering in the pom.xml is now just major.minor whereas the git numbering will keep its three numbers.

1st release

This is the 1st release of iirj which I created based on the iir1 library. Thanks for all who have provided feedback and weeded out bugs.