Allow setting a line timeout in MessageSiphon

Previously, the MessageSiphon class would read characters from an
InputStream and then push them to the passed MessageConsumer one line at
a time.

Now, you can specify a line timeout. Normally, messages are still
processed line by line, but if no line ending is received within the
specified timeout (counting from the first character in the line), then
the incomplete line is passed on as a message, without waiting for the
line ending.

This feature is used for the uploader command output. In particular,
this allows the avrdude progress bar to be shown in the IDE as expected,
character by character (previously, the entire progress bar would be
buffered, making it show up completely at the end of the upload).
Reduce avrdude verbosity

Previously, when verbose uploads were enabled, avrdude was run with four
-v options, causing it to dump all raw bytes exchanged with the
bootloader. This floods the console so much that meaningful output
mostly disappears.

Most users probably want to enable verbose mode just to see what avrdude
command is ran. Furthermore, users that benefit from the raw bytes
dumped are perfectly capable of either running avrdude manually, or
modifying platform.txt. Given that, running avrdude with just one  -v
should be plenty.

This fixes #891.
Merge remote-tracking branch 'ide-1.5.x-avrdude' into ide-1.5.x