Tax system and small fixes

Added tax calculator. if you earned nothing, default tax is 40%. If you
earned a billion derp, the default tax is 90%. Anything in between
scales on a logarithmic function.

Added a blinking cursor to the textpanel, as well as detecting whether
its selected.

Added check on upgrade numbers for the buttonclicker to return exactly
1,000,000 derp instead of 999,999.9999999 derp fo rthe last upgrade.

Added greetings for Brian's Computer, my computer, and jacob's computer
when making a new character.

Changed the derps draw value on the upgradescreen to use the
displayvalue, instead of the short display value.
Modified Startup message to include noland's pc