Moved searchPackage() to parse.go.

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Fixes allowing blanks of the begging of ImportDecl.

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Added parserFuncSignature().

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>