fix-golang-types-conversion

[timmyb32r]

Experimented with my .ksy-file (https://pastebin.com/M4vQDJVA) - found out, that go-generated sources not compiled, bcs of type conversion:

cannot use (int(this.MapHeader) >> 4) & 15 (value of type int) as uint8 value in assignment

used cursor to fix it - with this fix, go-generated sources compiles fine.
I'm not a guru with scala, but hope this fix will be useful.

[nzoschke]

The compiler also emits broken go for this ksy:

https://raw.githubusercontent.com/Deep-Symmetry/crate-digger/d95c444bde4bec6763cbbffd1a405dda0cc08750/src/main/kaitai/rekordbox_pdb.ksy

I confirmed this patch works

git clone -b fix-golang-types-conversion --depth 1 \
  https://github.com/timmyb32r/kaitai_struct_compiler.git /tmp/kaitai_struct_compiler
cd /tmp/kaitai_struct_compiler && sbt compilerJVM/universal:packageBin
cd - && unzip -qo /tmp/kaitai_struct_compiler/jvm/target/universal/kaitai-struct-compiler-0.12-SNAPSHOT.zip -d /tmp

# Download latest .ksy
curl -Lo rekordbox_pdb.ksy \
  https://raw.githubusercontent.com/Deep-Symmetry/crate-digger/d95c444bde4bec6763cbbffd1a405dda0cc08750/src/main/kaitai/rekordbox_pdb.ksy

# Compile to Go
/tmp/kaitai-struct-compiler-0.12-SNAPSHOT/bin/kaitai-struct-compiler \
  -t go --go-package pdb --outdir . rekordbox_pdb.ksy