Bugfix plotting function

Range of xlim and ylim was not computed correctly in diffExpr.
For B&W printers, pch was changed along with colors.
Help file updated accordingly.
new MAplot functui
Cleanup and plot axis labels

Cleaned up the code of plotting functions with more spaces around
assignment operators.
Appropriate labels for the axes of the MA plot.
Bugfix: diffExpr plot function

Remaining variable names of the manual tests present in the package.
Replaced by function variable names.
added MA plot origin line
Solved most issues reported by CMD check

Corrected all but one R CMD check errors and warning.
Error relates to the production of the PDF version of the manual.
Delete HudsonRIF_1.0.zip

No compiled filed in repository
Updated version number
gitignore should be the same across the clients
Explicit email address and Paul as coauthor
Fixes #6

Updated help file for wrapper Hudson function
Fixes #7

Added one reference from Hudson (2010).
PMID is now visible and also contains the URL to the Pubmed abstract.
One step further for #2

I will create one parameterCheck function for each wrapper function. The
naming rule for checking function will be:
parameterCheck.<calling function>
Fixes #2

Defined parameter-checking functions.
Each is dedicated to a given wrapper function.
These checking function should be named paramCheck<calling function>.
Update README.md
Merge pull request #9 from kevinrue/Hudson.package

Application of Hudson package changes to master branch.