Issues with Pedantic compiling

[xMAC94x]

Hey,
while installing the library in my project i got 2 compiler warnings due to my pedantic settings ("/W4" under Windows, "-Wall -Wextra -Werror -Wno-long-long -Wpedantic" under linux).

It would be cool if you could fix them in the original code, this is the diff i used to fix both errors, however you should have a brief look the solution because i just started working with c++:

1st Error: compiler warning because of possible lost of data when converting size_t to unsigned
2nd Error: isspace returns an int, but the function should return a bool

 backward.hpp
@@ -435,7 +435,7 @@ struct Trace {
 		addr(0), idx(0) {}
 
 	explicit Trace(void* addr, size_t idx):
- 		addr(addr), idx(idx) {}
+ 		addr(addr), idx(unsigned(idx)) {}
 };
 
 struct ResolvedTrace: public Trace {
@@ -1520,7 +1520,7 @@ public:
 		// What a good boy am I.
 		struct isspace {
 			bool operator()(char c) {
- 				return std::isspace(c);
+ 				return std::isspace(c) != 0;
 			}
 		};

[bombela]

We should probably change the type of the attribute idx to size_t.

[HorstBaerbel]

We should probably change the type of the attribute idx to size_t.

And compile with warnings==errors.
There's some more warnings in

backward-cpp/backward.hpp

Line 3618 in 5ffb2c8

EnumProcessModules(process, &module_handles[0],

ff (I suppose, I don't have the git version) due to the conversion from size_t to DWORD.