[R] R logo size in package information tab of Rstudio

[Marc Girondot]

Two different sizes of R logo are shown in Rstudio in the Help at the 
package level.

For example, numderiv shows a nice discreet logo located at (in MacosX):
/Library/Frameworks/R.framework/Versions/3.3/Resources/doc/html/logo.jpg
whereas packrat shows a huge logo located at:
/Library/Frameworks/R.framework/Versions/3.3/Resources/doc/html/Rlogo.svg

The choice between both depends on the path indicated in the file 
Index.html located in html folder for each package.

It would be better to have svg version of Rlogo.svg of the same size 
than logo.jpg (I have converted the Rlogo.svg into the same size than 
logo.jpg and it looks much better whit the new version).

Sincerely

Marc