add go.mod, go mod tidy

fix #17: proper embedded alignment of handleCounter

amd32 (raspberrypi) requires specific alignment for atomic operations to
work, or else you'll get "panic: runtime error: invalid memory address
or nil pointer dereference". Turns out this alignment is important for
embedded structs as well.
Embedding as the first member in the struct, and putting the atomic
field at the start of the embedded struct makes the alignment correct.

expose FSCache, CacheReader and add CacheReader.Size

Merge pull request #14 from wolfrace/cache_limits_v2

Cache limits with LRU v2

Merge pull request #14 from wolfrace/cache_limits_v2

Cache limits with LRU v2

#13 FileSystem RemoveAll() recreates the root dir, or else it's unusable

#13 FileSystem RemoveAll() recreates the root dir, or else it's unusable

Merge branch 'master' of https://github.com/djherbis/fscache

using github.com/djherbis/atime