First pass at a dex file reader---still doesn't actually produce an AST, and it runs too slow---checking in before I start hacking
Added a new dex-reader that returns an array of class definitions.

added .*.sw? and .sw? to avoid getting vim swap files; addes *.class in
src directory to avoid committing sources
   .gitignore, src/.gitignore

Added DexReader class that is initialized with a dex file name and
reads the dex file producing a representation of the dex code contained
in the dex file using ClassDef, FieldDef, MethodDef, and Instruction
records along with some intermediate classes. The representation
follows from the file format, though places where strings, types,
methods, or fields are indexed are linked to directly, and branching
instructions or instructions that require data from the instruction
stream are patched to have this data in the instruction (this means
there are no explicit labels in the bytecode representation).  Source
information is tagged directly into the instruction, when available.

src/com/ucombinator/dalvik/AST/{ClassDef,DexReader,FieldDef,Instruction,
MethodDef}.scala