Big refactoring for modern Linux and adding documentation

[mkgrgis]

In this PR

• add iserver_ prefix for utils
• change KOI-R READMEs to UTF-8
• add OSCAR documentation by author of Iserverd
• add V3G documentation by author of Iserverd
• delete trailing \t or white spaces across *.cpp and *.h
• fix emal3 warning in db_convert
• delete default DB connection properties for iserver_db_convert because of this is utility for very rare usage
• improve diagnostics and console info output for iserver_db_check
• add draft of Systemd service for Iserverd
• fix documentation images
• move doc to README directory
• add isdwm administrative web utility for Iserverd as contrib/isdwm
• add modern README.md

@namikiri , please carefully read all my changes and feel free to ask about reasons.

[namikiri]

Hello. Does this fix the ability to start iserverd on x86-64 yet?

[mkgrgis]

Hello. Does this fix the ability to start iserverd on x86-64 yet?

No. This PR doesn't change any network part of code - only adopts to modern utility naming conventions and code linters. For this ability in future I have added documentation to compare implementations with requirements.

[mkgrgis]

Hello. Does this fix the ability to start iserverd on x86-64 yet?

@namikiri , iserverd is successfully compilable. Also it starts before and after my PR, but doesn't work as expected. I think the error is in network layer. This PR tries to decrease number of warnings from compilers and installers.