Building WebUpdater fails in library code...

BosseB:
Yet another question...
Now that I have modified the webpage of the WebUpdater library I am in a situation where I have a modified file that is not residing in my project directory.
I need to somehow include this in Subversion for version control, but where is it actually located?
If I right-click the tab with the file it says:
TCP_UART_ESP/libraries/ESP8266HTTPUpdateServer/src/ESP8266HTTPUpdateServer.cpp
But when I look in my project directory I can find TCP_UART_ESP/libraries, but this directory is empty, no files at all!
So it seems like the actual code is located somewhere else entirely...
How do people manage to keep track of changes in version control (Subversion) for Arduino projects?
This is my first real such project....

the content of core and libraries in Sloeber project are Eclipse links. they are there for C++ indexer and your reference.

Isn't in he library a constructor or method to set custom html from sketch?