matlib 0.8.0

• add a vignette on properties of determinants (`det-ex1`)
• add a vignette on evaluation of determinants (`det-ex2`)
• add vignette on matrix inverse (`inv-ex1`)
• now use travis-ci to check builds
• add vignette on matrix inverse using EROs (`inv-ex2`)
• extended use of geometric diagrams in vignettes
• add vignette on generalized inverse (`ginv`)
• added `J()` for unit vectors, matrices
• added `LU()` for LU decomposition

# matlib 0.7.3

• Changed gaussianElimination() by defining local ERO functions to make the algorithm clearer; in verbose mode, show each ERO.
• Added a draw argument to `vectors3d()` and `arrows3d()`, which defaults to TRUE. If FALSE, just returns returns the "reg.length" to help in scaling.
• Optionally scale error spheres (and circles) produced by regvec3d() so that they project confidence intervals on the x1 and x2 axes.
• Small cosmetic changes to regvec3d().
• `showEqn()` and `gaussianElimination()` get `latex` arguments, to print results in LaTeX format [thx: Phil Chalmers]

# matlib 0.7.2

• added argument `error.sphere` to `plot.regvec3d()` [JF]
• remove use of `lengths()` in `corner()` to avoid R version dependency

# matlib 0.7.0

• use `corner()` in vectors3d.Rd
• added `arc()` for 2D, 3D vector diagrams to show angles between vectors
• added `regvec3d()` for 2D, 3D vector diagrams representing a bivariate multiple regression model, `lm(y ~ x1 + x2)` [thx: John Fox]
• added internal `.arrows()` to produce nice arrows in 2D `vector()` diagrams
• fixed numerous small problems in vector diagrams
• fixed some erroneous statements in vignettes
• `showEqn()` now aligns terms vertically and prints without quotes
• reversed sense of `absolute` in `points_on_line()` and clarified documentation

# matlib 0.6.0

• added `vandermode()` function
• added `vec()` convenience function to vectorize a matrix
• added `is_square_matrix()` tests
• added `power_method()`, power method for dominant eigenvector [thx: Gaston Sanchez]
• added `arrows3d()` for 3D geometric diagrams
• added `vectors3d()` for 3D geometric diagrams
• added `corner()` for 2D, 3D geometric diagrams
• added more documentation content to `man/matlib.Rd` from `README.md`

# matlib 0.5.2

• added `swp()` function
• added `vignette("gramreg")` - Gram-Schmidt Orthogonalization and Regression

# matlib 0.5.1

• added `len()` convenience function for Euclidean lengths
• added `plotEqn3d()` function using `rgl` to plot equations in 3 unknowns
• reorganized `matlib.R` to become a package .Rd document
• renamed `proj()` -> `Proj()` to avoid conflict with `stats::proj()`
• added `vectors()` for plotting geometric diagrams
• added vignette("linear-equations") - Solving Linear Equations

# matlib 0.4.1

Initial CRAN release