
When plotting text, do a complete dummy run through the code to parse
escape sequences in order to calculate the string length correctly,
including font changes, subscript, superscript etc.

Fixes bug visible on example 1 where the titles were not correctly
centred on the graph using the psttf driver.

svn path=/trunk/; revision=7327

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot