Zero determinant tests added.
Determinant by LU decomposition fixed (issue #91)
adds test AbtractMatrixTest.testRank_4x4_2()
fixes method AbtractMatrix.rank()
replaces invocations of set()/get() with update()
Merge pull request #97 from ewaldgrusk/fix_abstractmatrix_rank

Fixes #94
added credits for Ewald
Fixed bug in SVD (reported by Jonathan Edwards)
fixes #98
fixes #91
fixes #99
fixes #101
fixed a typo
added contributors how-to
added TODO
Refactored tests for CholeskyDecompositor. Added mock matrix class.
Refactored all decompositor's tests
Merge pull request #104 from hisohito/master

Refactored tests for Decomposition
Merge remote-tracking branch 'upstream/master'

Conflicts:
	src/main/java/org/la4j/matrix/AbstractMatrix.java
Create AbstractMatrix.java