Swap configuration handling for Elektra

[kodebach]

This replaces the hand-written INI parser for loading configurations with libelektra. The PR was implemented at the request of @haraldg.

Among the many benefits of using Elektra are:

• Automatic support for many different configuration file formats.
• Users can choose any of the supported formats without any change to lcdproc.
• Configuration parsing is based on a specification that is automatically validated on start-up.
• Command-line options and environment variables are processed automatically by Elektra as well.
• Tooling support for manipulating the configuration. Including the ability to merge upstream configuration changes into your modified configuration.

However, this PR is not finished. Only a handful of drivers have been updated (see list below). The documentation hasn't been updated at all. Instead information on how Elektra is used was added in docs/elektra. Also, since I do not own the necessary hardware, the updated drivers have not been tested. Testing was mostly done with the curses driver.

I likely won't have much time to work on this going forward. Therefore, I welcome anyone who wants to help out with this PR. To get started take a look at the documentation in docs/elektra (°) and if anything is unclear feel free to ask. We would especially appreciate, if people tested the already updated drivers.

(°) Note: you don't actually need to use master the latest relase of Elektra should work fine.

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Updated drivers:

• bayrad
• cfontz
• cfontzpacket
• curses
• cwlnx
• ea65
• eyeboxone
• futaba
• g15
• glcd
• glcdlib
• glk
• hd44780
• icp_a106
• imon
• imonlcd
• iowarrior
• irman
• joy
• lb216
• lcdm001
• lcterm
• linux_input
• lirc
• lis
• md8800
• mdm166a
• ms6931
• mtc_s16209x
• mtxorb
• mx5000
• noritakevfd
• olimex_mod_lcd1x9
• picolcd
• pyramid
• rawserial
• sdeclcd
• sed1330
• sed1520
• serialpos
• serialvfd
• shuttlevfd
• sli
• stv5730
• svga
• t6963
• text
• tyan
• ula200
• vlsys_m428
• xosd
• yard2lcd