Add non-static LastModified(void) method
Style and consistency changes

Add LOC in front of all logs, some of them had it, some didn't.
Not having it made it difficult to identify where some particular logs originated from as there are several areas showing the same text
Prevent playback to exit early should backend's writes be delayed

Typical scenario is when using liveTV and being very close to real time TV: should the backend take more than 360ms between two writes, the reader would treat it as an EOF and abort the read.

Whenever we open a file in write mode, we add it to a global dictionary. When reaching an EOF, we can then check if the file is going to be written to again.

We can also remove all EOF retries in FileRingBuffer::safe_read() as we definitely know now if we did reach EOF (as we check against the file size).
This allows for almost instantaneous program transition in live TV.