Support escaped newline characters in macro identifiers

An example of a fixed bug follows. For the macro
    #define	          \
macro\
\
Iden\
tifier(x,\
    y)x 		y
- before this commit the tooltip contained:
    Macro: macroIdentifier
    Body: \
macro\
\
Iden\
tifier(x,\
y)x y
- at this commit the tooltip contains:
    Function macro: macroIdentifier(x, \ y)
    Body: x y

Ideally `y` should not be preceded by `\ ` in the tooltip. However
removing all escaped newlines requires adding more code and bears a risk
of wrong parsing. The current tooltip is already much more readable than
the parsed C++ code.