Tweaked chunks per bulk packet down again (fixes #145).
Added various command-line options.
Created a foundation for adding more options.
Currently implemented: --port, --host and --onlinemode

Some server hosters, especially those who have payment options on a per-slot basis, customize runtime parameters to restrict server owners from exceeding their limits. Glowstone currently has limited support for command line options.

This commit adds a foundation for command-line options and implements --host, --port and --onlinemode

This commit also formats the help message that it shown when running GlowStone with the --help switch.
Fixed gradle manifest reference. Thanks @Grinch, @scooterboo, @lukespragg.
Changed wgen to treat 128 as world height in all cases (fixes #151).
Corrected when fallback commands are registered.
Added generateExtBlockSections support and handled generator errors better.
Revamped bulk sending to split chunks by how big they are.
Fixed InteractEntityMessage decoding (fixes #163).
Fixed decoding of client brand, some PluginMessage tidying (fixes #161).
Fixed sneaking and sprinting handling in PlayerActionHandler (fixes #165).
Tidied error messages on unclean disconnects (fixed #110).
Implements 1.8 codecs (0x41 up to 0x49)

Implement ServerDifficulty codec.
Implement CombatEvent codec.
Add 0x43 (Camera).
Packet 0x48 codec added.
Packet 0x44 added (WorldBorder)
Packet 0x45 added. (Title). Some formatting.
Add 0x49 (Entity update NBT). Using varLong now in WorldBorder.

Signed-off-by: William Lebel <lebelwilliam@gmail.com>