Replaced Unneeded ToUpper call and concats.

The ToUpper() function call can be removed by changing the "x" to "X".
Additionally, the PadLeft() call performs the same function as the while
loop, and does it faster.

The execution time with the changed code is half of what it was before.
Moved Calls Within Loops to Outside.

The changes made - combined with the changes to GetHexString - reduced
execution time per call from 12ms to 7ms.
Improved Exec Time of Disassembly Paint

Moved repeated MeasureText() calls to the same font and string outside
the loop.

Stored result of CPU.Breakpoints count in a variable to avoid
re-evaluating the list to get the same result.

Reduced execution time per call from 4ms to 2.8ms.
Fixed Style Changes, GetHexString ToString Call.
Merge pull request #43 from Measter/master

Improved Execution Times for Two Paint functions, and GetHexString.