Fix #540 Improved ConfigTool UI

- Move directory setting from General to Recording tab
- Put record to file options before record to stream options
- Improved resizing of ConfigTool
- Fixed close button size inconsistency
- Add Recording tab heading
- Recording and General tab section headers larger and bold
- Sub-heading font size determined at runtime
- Made widgets in Recording tab fixed size
- Capitalized the name in AboutWidget
- Add translations
- Directory button says "Browse..."
- Renamed mainlayout to mainLayout for AboutWidget
- Rename MiscGroupBox and MiscLayout to proper case
Add Instructions to Installation for Development

An introductory paragraph has been added to the "Installing Freeseer
for Development" section, giving an overall summary of how to install
Freeseer for development. It links to the guide on how to fork and
clone the project at the beginning of the section instead of the end.

In addition, the dollar signs $ have been removed from any command
line instructions for consistency and clarity.

Related to #442
Close #599
:memo: Edit copy for installing Freeseer for dev

Make it more concise and put steps in list-form.

[skip ci]
Close #597 Document how to install Freeseer in editable mode

[skip ci]