Release 2.5.2

[earlephilhower]

Changes since 2.5.1 (to 2.5.2)

Core

• Add explicit Print::write(char) (Add explicit Print::write(char) #6101)

Build system

• Fix typo in elf2bin for QOUT binary generation (Fix typo in elf2bin for QOUT binary generation #6116)
• Support PIO Wl-T and Arduino -T linking properly (Support PIO Wl-T and Arduino -T linking properly #6095)
• Allow *.cc files to be linked into flash by default (Allow *.cc files to be linked into flash by default #6100)
• Use custom "ElfToBin" builder for PIO (Use custom "ElfToBin" builder #6091)
• Fail if generated JSON file cannot be read (Fail if generated JSON file cannot be read #6076)
• Moved 'Dropping' print from stdout to stderr in drop_versions.py (Moved 'Dropping' print from stdout to stderr in drop_versions.py #6071)
• Fix PIO issue when build environment contains spaces (Fix issue when build environment contains spaces #6119)

Libraries

• Remove deadlock when server is not acking our data (Remove deadlock when server is not acking our data #6107)
• Bugfix for stuck in write method of WiFiClient and WiFiClientSecure until the remote peer closed connection (Bugfix for stuck in write method of WiFiClient and WiFiClientSecure until the remote peer closed connection #6104)
• Re-add original SD FAT info access methods (Re-add original SD FAT info access methods #6092)
• Make FILE_WRITE append in SD.h wrapper (Make FILE_WRITE append in SD.h wrapper #6106)
• Drop X509 after connection, avoid hang on TLS broken (Drop X509 context after successful server verification to save heap space #6065)