Replace "\n" with std::endl in all logging output

[ianhinder]

Logging output is using an explicit "\n" to end the line. This leaves the output buffered. This should be changed to std::endl, because that includes automatic line buffering. Currently, when the output is directed to a file, it only updates once the buffer is full, which is annoying, as you think it has hung. There are explicit calls to "flush" in bici.cc which are presumably designed to get around this.

Note that there are 136 occurrences of "\n" in the code, so this should be done when nobody is working on large-scale changes, to avoid conflicts.

$ grep '\\n' bici.cc header/*.h|wc -l
     136