Improve formatting & consistency of logging messages

[ubruhin]

Remove "(:0)" in logging messages of release builds

In release builds, typically __FILE__ and __LINE__ are not set. But currently these values are still output on each logging line (i.e. on stderr), which lead to "(:0)". Since this is useless, let's hide this if file/line are unknown.

Improve formatting & consistency of logging messages

Documented and applied the following guidelines to ensure a consistent look of console output:

• Logging messages shall not be translated, i.e. don't use tr() for them.
• Output real sentences, starting with uppercase letter and ending with a period. Exceptions are allowed for something like "Invalid parameter: foo".
• Try to output messages before the corresponding operation is performed. This helps to debug crashes since you see the last started operation. Use imperative language and end such messages with "...", for example "Save project...".
• Output native file paths, not UNIX filepaths.

Example

[  INFO   ] LibrePCB 0.2.0-unstable (fec46c039)
[  INFO   ] Qt version: 5.15.5 (compiled against 5.15.5)
[  INFO   ] Resources directory: "/home/me/LibrePCB/share/librepcb"
[  INFO   ] Application settings: "/home/me/.config/LibrePCB/LibrePCB.ini"
[DEBUG-MSG] Network access manager thread started.
[DEBUG-MSG] Successfully loaded stroke font "/home/me/LibrePCB/share/librepcb/fontobene/newstroke.bene" with 2573 glyphs.
[DEBUG-MSG] Recently used workspace: "/home/me/LibrePCB-Workspace"
[DEBUG-MSG] Open workspace data directory "/home/me/LibrePCB-Workspace/data"...
[DEBUG-MSG] Load workspace settings...
[DEBUG-MSG] Successfully loaded workspace settings.
[DEBUG-MSG] Load workspace library database...
[DEBUG-MSG] Successfully loaded workspace library database.
[DEBUG-MSG] Successfully opened workspace.
[DEBUG-MSG] Workspace library scanner thread started.
[DEBUG-MSG] Start workspace library scan in worker thread...
[DEBUG-MSG] Workspace libraries indexed: 42 libraries in 18 ms.
[DEBUG-MSG] Open project "/home/me/LibrePCB-Workspace/projects/can2usb/can2usb.lpp"...
[DEBUG-MSG] Found stroke font: "newstroke.bene"
[DEBUG-MSG] Start loading stroke font  "/home/me/LibrePCB-Workspace/projects/can2usb/resources/fontobene/newstroke.bene" in worker thread...
[DEBUG-MSG] Load project metadata...
[DEBUG-MSG] Successfully loaded project metadata.
[DEBUG-MSG] Load project settings...
[DEBUG-MSG] Successfully loaded project settings.
[DEBUG-MSG] Load project library...
[DEBUG-MSG] Successfully loaded 17 symbols.
[DEBUG-MSG] Successfully loaded 14 packages.
[DEBUG-MSG] Successfully loaded 17 components.
[DEBUG-MSG] Successfully loaded 16 devices.
[DEBUG-MSG] Successfully loaded project library.
[DEBUG-MSG] Load circuit...
[DEBUG-MSG] Successfully loaded circuit.
[DEBUG-MSG] Successfully loaded 1 schematics.
[DEBUG-MSG] Successfully loaded stroke font "/home/me/LibrePCB-Workspace/projects/can2usb/resources/fontobene/newstroke.bene" with 2573 glyphs.
[DEBUG-MSG] Successfully loaded 1 boards.
[DEBUG-MSG] Successfully loaded project.
[DEBUG-MSG] Save project...
[DEBUG-MSG] Save project files to transactional file system...
[DEBUG-MSG] Successfully saved project.
[DEBUG-MSG] Closed project "/home/me/LibrePCB-Workspace/projects/can2usb/can2usb.lpp".
[DEBUG-MSG] Network access manager thread stopped.
[DEBUG-MSG] Workspace library scan aborted after 4706 ms.
[DEBUG-MSG] Workspace library scanner thread stopped.
[DEBUG-MSG] Exit application with code 0.