Fix a typo pointed out by @thecow275.

Also, use the deprecated notification system which respects the
deprecated_lua_api_handling setting.

Recommend mod screenshot size in lua_api.txt
Adjust displayed screenshot size of texture packs
Document texture pack files in lua_api.txt

 - Use local variables for tabs in place of globals
 - Merge together if statements where possible
 - Replace manual table searching code with indexof where possible

Additionally, fix misc. code style issues

Change the name for texture pack description files from "info.txt" to "description.txt" in order to keep the naming consistent between description files for both mods and texture packs.

Also add backwards compatibility for texture packs that use "info.txt", and note in the log that "info.txt" is depreciated.

Signed-off-by: Craig Robbins <kde.psych@gmail.com>

Fix crash on using cursor keys in client menu without selected server
Add support for non fixed size tabviews