A test for "wt" function.

The proposed test checks that "wt" command indeed creates files in the current directory with correct specified size.
EXPECT_ERR description

Added description for EXPECT_ERR. Mentioned that EXPECT only applies to stdout. Reformatted text to fit "EXPECT_ERR (optional)".
Fix "cmd_system: !echo "test""
Merge pull request #40 from jvoisin/master

Fix "cmd_system: !echo "test""
add NX/ASLR detection for PE tests
small fix
Fix wrong ARC4 test
Remove BROKEN mark from fixed tests
Fix cmd_pdf_dwarf
Fix anal: x86_32
Refine 8051 tests
Fix wrong 8051 JNB test
Merge pull request #42 from jvoisin/master

Fix cmd_pdf_dwarf
Fix broken udis86 tests
first CoST tests
small fixes
refactor tests
add test on normal && normal64
move PE to format
refactoring