OUString: reduce temporaries/concatenated appends + minor optimizations
OUString: reduce temporaries/concatenated appends + minor optimizations

Change-Id: I30ea3ee112ef65555bfa5d7f2b8e908bb394ca58

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core