reworked regex for multi-line concordance files

[dhicks]

patchKnitrSynctex was failing with this concordance file:

\Sconcordance{concordance:commentary.tex:commentary.Rnw:%
1 2 1 49 0 1 11 69 1 1 20 1 1 1 27 10 1 1 27 5 1 7 0 %
77 1 1 7}

I determined that the problem was that the regex pattern re assumed exactly two lines. I rewrote re to accommodate multiple lines. This led to errors in the line rleValues <- read.table(textConnection(parsed[[1]][i,5]));. I then determined that the problem was that this element of the regex results now contained non-numeric characters (%, \n, and }). This element is now passed through gsub to remove everything except digits and spaces. I tested the new version of patchKnitrSynctex in situ with the concordance file above and both forward and backward searching appears to be working correctly.