Report an error if a file has no end-of-line but it should

Fix #726

This requires fixing a regtest

regtest/tools/rt-make-grid/input-grid.data

@@ -9,4 +9,3 @@
    1.2300   0.0521   1.4068
    1.2600   0.1120   2.6873
    1.2900   0.2199   4.6183
-   1.3200   0.3948   7.1055
\ No newline at end of file

src/tools/IFile.cpp

@@ -237,6 +237,7 @@ IFile& IFile::getline(std::string &str) {
   if(eof && noEOL) {
     if(str.length()>0) eof=false;
   } else if(eof || err || tmp!='\n') {
+    if(str.length()>0) plumed_merror("file " + getPath() + " is not allowed to have a non-terminated line. Please add a newline at the end of the file");
     eof = true;
     str="";
     if(!err) fsetpos(fp,&pos);