Small error in Extended.lyx

[Jürgen Spitzmüller]

Section 5.2.1 states that
"Translating from LaTeX into LyX is performed by a Python script called 
tex2lyx."

However, tex2lyx is written in C++. 

I suggest
"Translating from LaTeX into LyX is performed by a converter called tex2lyx."

Jürgen