Fix an error when calling a method implemented in C by super() with arguments. This fix makes the following code workable:

Expected:

class MRBTime < Time; def self.new; super(2012, 4, 21); end; end
MRBTime.new # => Sat Apr 21 00:00:00 2012

Actual:

class MRBTime < Time; def self.new; super(2012, 4, 21); end; end
MRBTime.new # => can't convert nil into Integer (TypeError)
[ci skip] run spell checker on doc/debugger/README.md and fixed typos mentioned from @bovi and @rmosolgo; ref #2640
Merge pull request #2641 from sdottaka/super-fix

Fix an error when calling a method implemented in C by super() with argu...
fix heap-use-after-free
free return value of dirname()
free memory used by breakpoints
remove cast

C99+TC3, 7.19.7.1p2: [...] the fgetc function obtains that character as
an unsigned char converted to an int [...]
don't convert function pointer to object pointer
remove const type qualifier

clang 3.5.0 with -Wextra produces a -Wignored-qualifiers diagnostic.
Merge pull request #2645 from cremno/mrdb-fix-heap-use-after-free

mrdb: fix heap-use-after-free
use mrb_str_xxx_lit for mrdb.
should support recursive mlhs decomposition, e.g. (a,b),c = [1,2],3
Merge pull request #2648 from cubicdaiya/use_lit_for_mrdb

use mrb_str_xxx_lit for mrdb.
align indent of local variable names in codedump()
Fix String#slice! raise TypeError or return invalid value.
Merge pull request #2649 from tmtm/fix-string-slice

Fix String#slice! raise TypeError or return invalid value.
Merge branch 'master' of github.com:mruby/mruby
add missing null-termination
remove unnecessary _WIN32 preprocessor check

SIZE_MAX < UINT32_MAX is false on Win32 / Win64.
Merge pull request #2653 from cremno/remove-unnecessary-_win32-preprocessor-check

remove unnecessary _WIN32 preprocessor check