Add asciinema support for issue #145

[SH20RAJ]

Add Asciinema Support for Issue visit1985#145

This PR implements support for asciinema recordings in mdp presentations as requested in issue visit1985#145.

Features Added:

• New Syntax: Users can now embed asciinema recordings using the syntax [asciinema:cols:rows:filename]
• Key Binding: Added 'a' key binding to trigger asciinema playback during presentation
• Smart Playback: When 'a' key is pressed, mdp will suspend the ncurses interface, play the specified asciinema recording, and resume the presentation after playback
• Visual Indication: Asciinema placeholders are displayed as [ASCIINEMA] in blue with underline
• Proper Parsing: Updated URL counting and length functions to handle asciinema syntax

Files Modified:

• include/config.h - Added asciinema key binding
• src/viewer.c - Added asciinema detection and playback logic
• src/url.c - Added asciinema syntax recognition in counting/length functions

Testing:

• Successfully compiles without errors or warnings
• Asciinema syntax is properly recognized and displayed
• Key binding works as expected
• Playback functionality properly suspends and resumes mdp

Closes visit1985#145